Issue #1258 - Part 1: Import mailnews, ldap, and mork from comm-esr52.9.1

23 files changed, 2130 insertions, 0 deletions

diff --git a/mailnews/jsaccount/modules/JSAccountUtils.jsm b/mailnews/jsaccount/modules/JSAccountUtils.jsm
new file mode 100644
index 000000000..b5ce34682
--- /dev/null
+++ b/mailnews/jsaccount/modules/JSAccountUtils.jsm
@@ -0,0 +1,285 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This file implements helper methods to make the transition of base mailnews
+ * objects from JS to C++ easier, and also to allow creating specialized
+ * versions of those accounts using only JS XPCOM implementations.
+ *
+ * In C++ land, the XPCOM component is a generic C++ class that does nothing
+ * but delegate any calls to interfaces known in C++ to either the generic
+ * C++ implementation (such as nsMsgIncomingServer.cpp) or a JavaScript
+ * implementation of those methods. Those delegations could be used for either
+ * method-by-method replacement of the generic C++ methods with JavaScript
+ * versions, or for specialization of the generic class using JavaScript to
+ * implement a particular class type. We use a C++ class as the main XPCOM
+ * version for two related reasons: First, we do not want to go through a
+ * C++->js->C++ XPCOM transition just to execute a C++ method. Second, C++
+ * inheritance is different from JS inheritance, and sometimes the C++ code
+ * will ignore the XPCOM parts of the JS, and just execute using C++
+ * inheritance.
+ *
+ * In JavaScript land, the implementation currently uses the XPCOM object for
+ * JavaScript calls, with the last object in the prototype chain defaulting
+ * to calling using the CPP object, specified in an instance-specific
+ * this.cppBase object.
+ *
+ * Examples of use can be found in the test files for jsaccount stuff.
+ */
+
+const EXPORTED_SYMBOLS = ["JSAccountUtils"];
+var JSAccountUtils = {};
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cu = Components.utils;
+var Cr = Components.results;
+
+Cu.import("resource://gre/modules/Log.jsm");
+Cu.import("resource://gre/modules/Preferences.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+// Logger definitions.
+const LOGGER_NAME = "JsAccount";
+const PREF_BRANCH_LOG = "mailnews.jsaccount.log.";
+const PREF_LOG_LEVEL = PREF_BRANCH_LOG + "level";
+const PREF_LOG_DUMP = PREF_BRANCH_LOG + "dump";
+
+// Set default logging levels.
+const LOG_LEVEL_DEFAULT = "Info"
+const LOG_DUMP_DEFAULT = true;
+
+// Logging usage: set mailnews.jsaccount.log.level to the word "Debug" to
+// increase logging level.
+
+var log = configureLogging();
+
+/**
+ *
+ *  Generic factory to create XPCOM components under JsAccount.
+ *
+ *  @param aProperties   This a a const JS object that describes the specific
+ *                       details of a particular JsAccount XPCOM object:
+ *     {
+ *       baseContractID: string contractID used to create the base generic C++
+ *                       object. This object must implement the interfaces in
+ *                       baseInterfaces, plus msgIOverride.
+ *
+ *       baseInterfaces: JS array of interfaces implemented by the base, generic
+ *                       C++ object.
+ *
+ *       extraInterfaces: JS array of additional interfaces implemented by the
+ *                        component (accessed using getInterface())
+ *
+ *       contractID:     string contract ID for the JS object that will be
+ *                       created by the factory.
+ *
+ *       classID:        Components.ID(CID) for the JS object that will be
+ *                       created by the factory, where CID is a string uuid.
+ *      }
+ *
+ *   @param aJsDelegateConstructor: a JS contructor class, called using new,
+ *                                  that will create the JS object to which
+ *                                  XPCOM methods calls will be delegated.
+ */
+
+JSAccountUtils.jaFactory = function (aProperties, aJsDelegateConstructor)
+{
+  let factory = {};
+  factory.QueryInterface = XPCOMUtils.generateQI([Ci.nsIFactory]);
+  factory.lockFactory = function() {};
+
+  factory.createInstance = function(outer, iid)
+  {
+    if (outer != null)
+      throw Cr.NS_ERROR_NO_AGGREGATION;
+
+    // C++ delegator class.
+    let delegator = Cc[aProperties.baseContractID]
+                      .createInstance(Ci.msgIOverride);
+
+    // Make sure the delegator JS wrapper knows its interfaces.
+    aProperties.baseInterfaces.forEach(iface => delegator instanceof iface);
+
+    // JavaScript overrides of base class functions.
+    let jsDelegate = new aJsDelegateConstructor(delegator, aProperties.baseInterfaces);
+    delegator.jsDelegate = jsDelegate;
+
+    // Get the delegate list for this current class. Use OwnProperty in case it
+    // inherits from another JsAccount class.
+
+    let delegateList = null;
+    if (Object.getPrototypeOf(jsDelegate).hasOwnProperty("delegateList")) {
+      delegateList = Object.getPrototypeOf(jsDelegate).delegateList;
+    }
+    if (delegateList instanceof Ci.msgIDelegateList) {
+      delegator.methodsToDelegate = delegateList;
+    } else {
+      // Lazily create and populate the list of methods to delegate.
+      log.info("creating delegate list for contractID " + aProperties.contractID);
+      let delegateList = delegator.methodsToDelegate;
+      Object.keys(delegator).forEach(name => {log.debug("delegator has key " + name);});
+
+      // jsMethods contains the methods that may be targets of the C++ delegation to JS.
+      let jsMethods = Object.getPrototypeOf(delegator.jsDelegate.wrappedJSObject);
+      for (let name in jsMethods)
+      {
+        log.debug("processing jsDelegate method: " + name);
+        if (name[0] == '_') { // don't bother with methods explicitly marked as internal.
+          log.debug("skipping " + name);
+          continue;
+        }
+        // Other methods to skip.
+        if (["QueryInterface",  // nsISupports
+             "methodsToDelegate", "jsDelegate", "cppBase", // msgIOverride
+             "delegateList", "wrappedJSObject", // non-XPCOM methods to skip
+            ].includes(name)) {
+          log.debug("skipping " + name);
+          continue;
+        }
+
+        let jsDescriptor = getPropertyDescriptor(jsMethods, name);
+        if (!jsDescriptor) {
+          log.debug("no jsDescriptor for " + name);
+          continue;
+        }
+        let cppDescriptor = Object.getOwnPropertyDescriptor(delegator, name);
+        if (!cppDescriptor) {
+          log.debug("no cppDescriptor found for " + name);
+          // It is OK for jsMethods to have methods that are not used in override of C++.
+          continue;
+        }
+
+        let upperCaseName = name[0].toUpperCase() + name.substr(1);
+        if ('value' in jsDescriptor) {
+          log.info("delegating " + upperCaseName);
+          delegateList.add(upperCaseName);
+        }
+        else {
+          if (jsDescriptor.set) {
+            log.info("delegating Set" + upperCaseName);
+            delegateList.add("Set" + upperCaseName);
+          }
+          if (jsDescriptor.get) {
+            log.info("delegating Get" + upperCaseName);
+            delegateList.add("Get" + upperCaseName);
+          }
+        }
+      }
+
+      // Save the delegate list for reuse, statically for all instances.
+      Object.getPrototypeOf(jsDelegate).delegateList = delegateList;
+    }
+
+    for (let iface of aProperties.baseInterfaces)
+      if (iid.equals(iface)) {
+        log.debug("Successfully returning delegator " + delegator);
+        return delegator;
+      }
+    throw Cr.NS_ERROR_NO_INTERFACE;
+  };
+
+  return factory;
+}
+
+/**
+ * Create a JS object that contains calls to each of the methods in a CPP
+ * base class, that will reference the cpp object defined on a particular
+ * instance of the object. This is intended to be the last item in the
+ * prototype chain for a JsAccount implementation.
+ *
+ * @param aProperties see definition in jsFactory above
+ *
+ * @returns a JS object suitable as the prototype of a JsAccount implementation.
+ */
+JSAccountUtils.makeCppDelegator = function(aProperties)
+{
+  log.info("Making cppDelegator for contractID " + aProperties.contractID);
+  let cppDelegator = {};
+  let cppDummy = Cc[aProperties.baseContractID].createInstance(Ci.nsISupports);
+  // Add methods from all interfaces.
+  for (let iface of aProperties.baseInterfaces)
+    cppDummy instanceof Ci[iface];
+
+  for (let method in cppDummy) {
+    // skip nsISupports and msgIOverride methods
+    if (["QueryInterface", "methodsToDelegate", "jsDelegate", "cppBase", "getInterface"].includes(method)) {
+      log.config("Skipping " + method + "\n");
+      continue;
+    }
+    log.config("processing " + method + "\n");
+    let descriptor = Object.getOwnPropertyDescriptor(cppDummy, method);
+    let property = { enumerable: true };
+    // We must use Immediately Invoked Function Expressions to pass method, otherwise it is
+    // a closure containing just the last value it was set to.
+    if ('value' in descriptor) {
+      log.debug("Adding value for " + method);
+      property.value = function(aMethod) {
+        return function(...args) {
+          return Reflect.apply(this.cppBase[aMethod], undefined, args);
+        };
+      }(method);
+    }
+    if (descriptor.set) {
+      log.debug("Adding setter for " + method);
+      property.set = function(aMethod) {
+        return function(aVal) {
+          this.cppBase[aMethod] = aVal;
+        };
+      }(method);
+    }
+    if (descriptor.get) {
+      log.debug("Adding getter for " + method);
+      property.get = function(aMethod) {
+        return function() {
+          return this.cppBase[aMethod];
+        };
+      }(method);
+    }
+    Object.defineProperty(cppDelegator, method, property);
+  }
+  return cppDelegator;
+}
+
+// Utility functions.
+
+// Iterate over an object and its prototypes to get a property descriptor.
+function getPropertyDescriptor(obj, name)
+{
+  let descriptor = null;
+
+  // Eventually we will hit an object that will delegate JS calls to a CPP
+  // object, which are not JS overrides of CPP methods. Locate this item, and
+  // skip, because it will not have _JsPrototypeToDelegate defined.
+  while (obj && ("_JsPrototypeToDelegate" in obj)) {
+    descriptor = Object.getOwnPropertyDescriptor(obj, name);
+    if (descriptor)
+      break;
+    obj = Object.getPrototypeOf(obj);
+  }
+  return descriptor;
+}
+
+// Configure the logger based on the preferences.
+function configureLogging()
+{
+  let log = Log.repository.getLogger(LOGGER_NAME);
+
+  // Log messages need to go to the browser console.
+  let consoleAppender = new Log.ConsoleAppender(new Log.BasicFormatter());
+  log.addAppender(consoleAppender);
+
+  // Make sure the logger keeps up with the logging level preference.
+  log.level = Log.Level[Preferences.get(PREF_LOG_LEVEL, LOG_LEVEL_DEFAULT)];
+
+  // If enabled in the preferences, add a dump appender.
+  let logDumping = Preferences.get(PREF_LOG_DUMP, LOG_DUMP_DEFAULT);
+  if (logDumping) {
+    let dumpAppender = new Log.DumpAppender(new Log.BasicFormatter());
+    log.addAppender(dumpAppender);
+  }
+  return log;
+}
diff --git a/mailnews/jsaccount/modules/JaBaseUrl.jsm b/mailnews/jsaccount/modules/JaBaseUrl.jsm
new file mode 100644
index 000000000..21a10847a
--- /dev/null
+++ b/mailnews/jsaccount/modules/JaBaseUrl.jsm
@@ -0,0 +1,81 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const EXPORTED_SYMBOLS = ["JaBaseUrlProperties", "JaBaseUrl"];
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cr = Components.results;
+var Cu = Components.utils;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/jsaccount/JSAccountUtils.jsm");
+
+// A partial JavaScript implementation of the base server methods.
+
+const JaBaseUrlProperties = {
+
+  // The CPP object that delgates to CPP or JS.
+  baseContractID:     "@mozilla.org/jacppurldelegator;1",
+
+  // Interfaces implemented by the base CPP version of this object.
+  baseInterfaces:     [ Ci.nsIURI,
+                        Ci.nsIURL,
+                        Ci.nsIMsgMailNewsUrl,
+                        Ci.nsIMsgMessageUrl,
+                        Ci.msgIOverride,
+                        Ci.nsISupports,
+                        Ci.nsIInterfaceRequestor,
+                        ],
+
+  // We don't typically define this as a creatable component, but if we do use
+  // these. Subclasses for particular account types require these defined for
+  // that type.
+  contractID:         "@mozilla.org/jsaccount/jaurl;1",
+  classID:            Components.ID("{1E7B42CA-E6D9-408F-A4E4-8D2F82AECBBD}"),
+};
+
+function JaBaseUrl(aDelegator, aBaseInterfaces) {
+
+// Typical boilerplate to include in all implementations.
+
+  // Object delegating method calls to the appropriate XPCOM object.
+  // Weak because it owns us.
+  this._delegatorWeak = Cu.getWeakReference(aDelegator);
+
+  // Base implementation of methods with no overrides.
+  this.cppBase = aDelegator.cppBase;
+
+  // cppBase class sees all interfaces
+  aBaseInterfaces.forEach(iface => this.cppBase instanceof iface);
+}
+
+JaBaseUrl.prototype = {
+// Typical boilerplate to include in all implementations.
+  __proto__: JSAccountUtils.makeCppDelegator(JaBaseUrlProperties),
+
+  // Flag this item as CPP needs to delegate to JS.
+  _JsPrototypeToDelegate: true,
+
+  // QI to the interfaces.
+  QueryInterface: XPCOMUtils.generateQI(JaBaseUrlProperties.baseInterfaces),
+
+  // Used to access an instance as JS, bypassing XPCOM.
+  get wrappedJSObject() {
+    return this;
+  },
+
+  // Accessor to the weak cpp delegator.
+  get delegator() {
+    return this._delegatorWeak.get();
+  },
+
+  // Dynamically-generated list of delegate methods.
+  delegateList: null,
+
+  // Implementation in JS  (if any) of methods in XPCOM interfaces.
+
+};
diff --git a/mailnews/jsaccount/moz.build b/mailnews/jsaccount/moz.build
new file mode 100644
index 000000000..6e080b863
--- /dev/null
+++ b/mailnews/jsaccount/moz.build
@@ -0,0 +1,15 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+  'public',
+  'src'
+]
+
+EXTRA_JS_MODULES.jsaccount += [
+    'modules/JaBaseUrl.jsm',
+    'modules/JSAccountUtils.jsm',
+]
diff --git a/mailnews/jsaccount/public/moz.build b/mailnews/jsaccount/public/moz.build
new file mode 100644
index 000000000..a635ffca9
--- /dev/null
+++ b/mailnews/jsaccount/public/moz.build
@@ -0,0 +1,17 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'msgIDelegateList.idl',
+    'msgIOverride.idl',
+]
+
+EXPORTS += [
+    'msgJsAccountCID.h',
+]
+
+XPIDL_MODULE = 'msgjsaccount'
+
diff --git a/mailnews/jsaccount/public/msgIDelegateList.idl b/mailnews/jsaccount/public/msgIDelegateList.idl
new file mode 100644
index 000000000..dce1b0bb6
--- /dev/null
+++ b/mailnews/jsaccount/public/msgIDelegateList.idl
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * This interface provides a list of methods that should be delegated to
+ * a JsObject rather than a C++ XPCOM base object in JsAccount classes.
+ */
+
+[scriptable, builtinclass, uuid(627D3A34-F8A3-40eb-91FE-E413D6638D27)]
+interface msgIDelegateList : nsISupports
+{
+  /// Method name to delegate to JavaScript.
+  void add(in string aMethod);
+};
diff --git a/mailnews/jsaccount/public/msgIOverride.idl b/mailnews/jsaccount/public/msgIOverride.idl
new file mode 100644
index 000000000..cad1bf415
--- /dev/null
+++ b/mailnews/jsaccount/public/msgIOverride.idl
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+#include "msgIDelegateList.idl"
+
+/**
+ * Mailnews code typically has a C++ base class for objects, which is then
+ * specialized for each account type with a C++ subclass of the base class.
+ *
+ * This interface provides the ability of JavaScript-based account
+ * implementations to use the same C++ base classes as core objects, but
+ * use JavaScript to override methods instead of C++.
+ */
+
+[scriptable, uuid(68075269-8BBD-4a09-AC04-3241BF44F633)]
+interface msgIOverride : nsISupports
+{
+  /**
+   *
+   * A list of methods in the C++ base class that will be delegated to the JS
+   * delegate. This is calculated once, and then a fixed value is set to
+   * all subsequent instances so that it does not need to be recalculated each
+   * time. If the value has not yet been set, this will return a new instance.
+   */
+  attribute msgIDelegateList methodsToDelegate;
+
+  /**
+   * JavaScript-based xpcom object that overrides C++ methods.
+   */
+  attribute nsISupports jsDelegate;
+
+  /**
+   * C++ class used to implement default functionality. This is used when
+   * JavaScript methods want to call the base class default action, bypassing a
+   * possible JS override.
+   */
+  readonly attribute nsISupports cppBase;
+};
diff --git a/mailnews/jsaccount/public/msgJsAccountCID.h b/mailnews/jsaccount/public/msgJsAccountCID.h
new file mode 100644
index 000000000..330569312
--- /dev/null
+++ b/mailnews/jsaccount/public/msgJsAccountCID.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Contains the definitions of contract IDs for modules in JsAccounts.
+
+#ifndef _msgJsAccountCID_H_
+#define _msgJsAccountCID_H_
+
+#define JACPPURLDELEGATOR_CID \
+{ 0x1a0b778c, 0x2fe6, 0x4012, { 0xb4, 0xf3, 0xe8, 0x1c, 0xc, 0x11, 0x64, 0x9 } }
+#define JACPPURLDELEGATOR_CONTRACTID "@mozilla.org/jacppurldelegator;1"
+
+#define JACPPABDIRECTORYDELEGATOR_CID \
+{ 0x77b5592c, 0x5018, 0x436d, { 0xa4, 0x66, 0xc4, 0xe5, 0x44, 0x3a, 0x16, 0x69 } }
+#define JACPPABDIRECTORYDELEGATOR_CONTRACTID "@mozilla.org/jacppabdirectorydelegator;1"
+
+#define JACPPINCOMINGSERVERDELEGATOR_CID \
+{ 0x7aa11dd3, 0x5590, 0x4e01, { 0xbd, 0x87, 0x91, 0xf6, 0x02, 0x72, 0xd0, 0x1a } }
+#define JACPPINCOMINGSERVERDELEGATOR_CONTRACTID "@mozilla.org/jacppincomingserverdelegator;1"
+
+#define JACPPCOMPOSEDELEGATOR_CID \
+{ 0xcfcd1caa, 0x00d9, 0x40d0, { 0x83, 0x1e, 0x67, 0x38, 0x20, 0xe0, 0x4f, 0xc6 } }
+#define JACPPCOMPOSEDELEGATOR_CONTRACTID "@mozilla.org/jacppcomposedelegator;1"
+
+#define JACPPMSGFOLDERDELEGATOR_CID \
+{ 0xd6bd81fa, 0xb1d4, 0x424a, { 0x88, 0xea, 0xbb, 0x3e, 0xa8, 0x38, 0x1d, 0x50 } }
+#define JACPPMSGFOLDERDELEGATOR_CONTRACTID "@mozilla.org/jacppmsgfolderdelegator;1"
+
+#define JACPPSENDDELEGATOR_CID \
+{ 0x36fcb887, 0x2b04, 0x42d4, { 0x92, 0xc9, 0xae, 0xd2, 0xac, 0xa1, 0xd4, 0x5b } }
+#define JACPPSENDDELEGATOR_CONTRACTID "@mozilla.org/jacppsenddelegator;1"
+#endif
diff --git a/mailnews/jsaccount/readme.html b/mailnews/jsaccount/readme.html
new file mode 100644
index 000000000..317b3c227
--- /dev/null
+++ b/mailnews/jsaccount/readme.html
@@ -0,0 +1,56 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <title>JsAccount Usage and Architecture</title>
+  </head>
+  <body>
+    <h1>Overview</h1>
+    <p>JsAccount is a technology that allows message account types to be created
+      in Mozilla Mailnews code using JavaScript. Although this is primarily
+      targeted at allowing extensions to create new accounts, it might also be
+      useful as a bridge to convert existing account types from being C++ based
+      to JavaScript based.</p>
+    <h2>Existing C++-based architecture of mailnews accounts</h2>
+    <p>In mailnews code, an account type is a set of classes that allow
+      implementation of a messaging particular protocol. The account type is
+      given a short string identifier ("imap", "news", "pop3") and is then used
+      to create objects of the appropriate type by appending that string to the
+      end of a base XPCOM contractID. So, for example, to create an imap server,
+      you generate a contractID using a base ID,
+      NS_MSGINCOMINGSERVER_CONTRACTID_PREFIX
+      "@mozilla.org/messenger/server;1?type=", then append "imap" to get:</p>
+    <p>@mozilla.org/messenger/server;1?type=imap</p>
+    <p>In the C++ code, there is a base object implementing shared
+      functionality. An account-specific class inherits that base functionality,
+      then extends it to represent the account-specific behavior that is needed.
+      This same basic concept is used to represent a whole series of classes
+      that are necessary to implement a specific mailnews account type.</p>
+    <p>For the server example, there is a base class named
+      nsMsgIncomingServer.cpp that implements that base interface
+      nsIMsgIncomingServer.idl. For imap, there is a specific class
+      nsImapIncomingServer.cpp that inherits from nsMsgIncomingServer.cpp,
+      overrides some of the methods in nsIMsgIncomingServer.idl, and also
+      implements an imap-specific interface nsIImapIncomingServer.idl. All of
+      this works fine using C++ inheritance and polymorphism.</p>
+    <p>Although JsAccount is intended mostly for mailnews accounts, the same
+      basic method of using a base class extended for specific types is also used
+      in other ways in mailnews code, including for addressbook types and views.
+      The technology may also be applied to those other object types as well.</p>
+    <h2>Role of JsAccount</h2>
+    <p>The JavaScript class system works very differently than the C++ system,
+      and you cannot use normal language constructs to override a C++ class with
+      a JavaScript class. What JsAccount allows you to do is to create XPCOM
+      objects in JavaScript, and use those objects to override or extend the
+      methods from the C++ base class in a way that will function correctly
+      whether those objects are executed from within C++ code or JavaScript
+      code. This allows you to create a new account using JavaScript code, while
+      using the same base class functionality that is used by the core C++
+      account types. Thus a new account type may be created in JavaScript-based
+      extension. The technology may also be used to create JavaScript
+      versions of existing account types in an incremental manner, slowly
+      converting methods from C++ to JavaScript.</p>
+    <p><br>
+    </p>
+  </body>
+</html>
diff --git a/mailnews/jsaccount/src/DelegateList.cpp b/mailnews/jsaccount/src/DelegateList.cpp
new file mode 100644
index 000000000..7d2bae30c
--- /dev/null
+++ b/mailnews/jsaccount/src/DelegateList.cpp
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DelegateList.h"
+
+// This class is used within JsAccount to allow static storage of a list
+// of methods to be overridden by JS implementations, in a way that can
+// be stored and manipulated in JS, but used efficiently in C++.
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS(DelegateList, msgIDelegateList)
+
+NS_IMETHODIMP DelegateList::Add(const char *aMethodName)
+{
+  // __FUNCTION__ is the undecorated function name in gcc, but decorated in
+  // Windows. __func__ will resolve this when supported in VS 2015.
+  nsCString prettyFunction;
+#if defined (_MSC_VER)
+  prettyFunction.Append(mPrefix);
+#endif
+  prettyFunction.Append(nsDependentCString(aMethodName));
+
+  mMethods.Put(prettyFunction, true);
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/DelegateList.h b/mailnews/jsaccount/src/DelegateList.h
new file mode 100644
index 000000000..943b3e726
--- /dev/null
+++ b/mailnews/jsaccount/src/DelegateList.h
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _DelegateList_H_
+#define _DelegateList_H_
+
+#include "nsISupports.h"
+#include "msgIDelegateList.h"
+#include "nsDataHashtable.h"
+
+namespace mozilla {
+namespace mailnews {
+
+// This class provides a list of method names to delegate to another object.
+class DelegateList : public msgIDelegateList
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_MSGIDELEGATELIST
+  DelegateList(const char *aWindowsPrefix) :
+    mPrefix(aWindowsPrefix)
+  { }
+  nsDataHashtable<nsCStringHashKey, bool> mMethods;
+
+protected:
+  virtual ~DelegateList() { }
+  nsCString mPrefix; // Windows decorated method prefix.
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+/*
+ * This macro is used in forwarding functions.
+ *   _interface: the interface being forwarded.
+ *   _jsdelegate: the name of the JS pointer that implements a particular
+ *                interface.
+ *
+ * You must follow the naming convention:
+ *   1) use mCppBase as the name of the C++ base class instance.
+ *   2) use mMethod as the name of the DelegateList object.
+ **/
+
+#define DELEGATE_JS(_interface, _jsdelegate) (\
+    _jsdelegate && mMethods && \
+    mMethods->Contains(nsLiteralCString(__FUNCTION__)) ? \
+       _jsdelegate : nsCOMPtr<_interface>(do_QueryInterface(mCppBase)))
+
+#endif
diff --git a/mailnews/jsaccount/src/JaAbDirectory.cpp b/mailnews/jsaccount/src/JaAbDirectory.cpp
new file mode 100644
index 000000000..7d9c16d78
--- /dev/null
+++ b/mailnews/jsaccount/src/JaAbDirectory.cpp
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JaAbDirectory.h"
+#include "nsISupportsUtils.h"
+#include "nsIFile.h"
+#include "nsIMsgHdr.h"
+#include "nsIMessenger.h"
+#include "nsMsgBaseCID.h"
+#include "nsComponentManagerUtils.h"
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS_INHERITED(JaBaseCppAbDirectory, nsAbDirProperty,
+                            nsIInterfaceRequestor)
+
+// nsIInterfaceRequestor implementation
+NS_IMETHODIMP JaBaseCppAbDirectory::GetInterface(const nsIID & aIID, void **aSink)
+{
+  return QueryInterface(aIID, aSink);
+}
+
+// Delegator
+NS_IMPL_ISUPPORTS_INHERITED(JaCppAbDirectoryDelegator,
+                           JaBaseCppAbDirectory,
+                           msgIOverride)
+
+// Delegator object to bypass JS method override.
+NS_IMPL_ISUPPORTS(JaCppAbDirectoryDelegator::Super,
+                  nsIAbDirectory,
+                  nsIAbCollection,
+                  nsIAbItem,
+                  nsIInterfaceRequestor)
+
+JaCppAbDirectoryDelegator::JaCppAbDirectoryDelegator() :
+  mCppBase(new Super(this)),
+  mMethods(nullptr)
+{ }
+
+NS_IMETHODIMP JaCppAbDirectoryDelegator::SetMethodsToDelegate(msgIDelegateList* aDelegateList)
+{
+  if (!aDelegateList)
+  {
+    NS_WARNING("Null delegate list");
+    return NS_ERROR_NULL_POINTER;
+  }
+  // We static_cast since we want to use the hash object directly.
+  mDelegateList = static_cast<DelegateList*> (aDelegateList);
+  mMethods = &(mDelegateList->mMethods);
+  return NS_OK;
+}
+NS_IMETHODIMP JaCppAbDirectoryDelegator::GetMethodsToDelegate(msgIDelegateList** aDelegateList)
+{
+  if (!mDelegateList)
+    mDelegateList = new DelegateList("mozilla::mailnews::JaCppAbDirectoryDelegator::");
+  mMethods = &(mDelegateList->mMethods);
+  NS_ADDREF(*aDelegateList = mDelegateList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaCppAbDirectoryDelegator::SetJsDelegate(nsISupports* aJsDelegate)
+{
+  // If these QIs fail, then overrides are not provided for methods in that
+  // interface, which is OK.
+  mJsISupports = aJsDelegate;
+  mJsIAbDirectory = do_QueryInterface(aJsDelegate);
+  mJsIAbCollection = do_QueryInterface(aJsDelegate);
+  mJsIAbItem = do_QueryInterface(aJsDelegate);
+  mJsIInterfaceRequestor = do_QueryInterface(aJsDelegate);
+  return NS_OK;
+}
+NS_IMETHODIMP JaCppAbDirectoryDelegator::GetJsDelegate(nsISupports **aJsDelegate)
+{
+  NS_ENSURE_ARG_POINTER(aJsDelegate);
+  if (mJsISupports)
+  {
+    NS_ADDREF(*aJsDelegate = mJsISupports);
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP JaCppAbDirectoryDelegator::GetCppBase(nsISupports** aCppBase)
+{
+  nsCOMPtr<nsISupports> cppBaseSupports;
+  cppBaseSupports = NS_ISUPPORTS_CAST(nsIAbDirectory*, mCppBase);
+  NS_ENSURE_STATE(cppBaseSupports);
+  cppBaseSupports.forget(aCppBase);
+
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/JaAbDirectory.h b/mailnews/jsaccount/src/JaAbDirectory.h
new file mode 100644
index 000000000..4ada7c761
--- /dev/null
+++ b/mailnews/jsaccount/src/JaAbDirectory.h
@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _JaAbDirectory_H_
+#define _JaAbDirectory_H_
+
+#include "DelegateList.h"
+#include "msgIOverride.h"
+#include "nsAbDirProperty.h"
+#include "nsAutoPtr.h"
+#include "nsDataHashtable.h"
+#include "nsIInterfaceRequestor.h"
+
+namespace mozilla {
+namespace mailnews {
+
+/* Header file */
+
+// This class is an XPCOM component, usable in JS, that calls the methods
+// in the C++ base class (bypassing any JS override).
+class JaBaseCppAbDirectory : public nsAbDirProperty,
+                             public nsIInterfaceRequestor
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIINTERFACEREQUESTOR
+  JaBaseCppAbDirectory() { }
+
+protected:
+  virtual ~JaBaseCppAbDirectory() { }
+
+};
+
+class JaCppAbDirectoryDelegator : public JaBaseCppAbDirectory,
+                                  public msgIOverride
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_MSGIOVERRIDE
+
+  NS_FORWARD_NSIABDIRECTORY(DELEGATE_JS(nsIAbDirectory, mJsIAbDirectory)->)
+  NS_FORWARD_NSIABCOLLECTION(DELEGATE_JS(nsIAbCollection, mJsIAbCollection)->)
+  NS_FORWARD_NSIABITEM(DELEGATE_JS(nsIAbItem, mJsIAbItem)->)
+  NS_FORWARD_NSIINTERFACEREQUESTOR(DELEGATE_JS(nsIInterfaceRequestor, mJsIInterfaceRequestor)->)
+
+  JaCppAbDirectoryDelegator();
+
+private:
+  virtual ~JaCppAbDirectoryDelegator() {
+  }
+
+  class Super : public nsIAbDirectory,
+                public nsIInterfaceRequestor
+  {
+    public:
+      Super(JaCppAbDirectoryDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      NS_DECL_ISUPPORTS
+      NS_FORWARD_NSIABDIRECTORY(mFakeThis->JaBaseCppAbDirectory::)
+      NS_FORWARD_NSIABCOLLECTION(mFakeThis->JaBaseCppAbDirectory::)
+      NS_FORWARD_NSIABITEM(mFakeThis->JaBaseCppAbDirectory::)
+      NS_FORWARD_NSIINTERFACEREQUESTOR(mFakeThis->JaBaseCppAbDirectory::)
+    private:
+      virtual ~Super() {}
+      JaCppAbDirectoryDelegator* mFakeThis;
+  };
+
+  // Interfaces that may be overridden by JS.
+  nsCOMPtr<nsIAbDirectory> mJsIAbDirectory;
+  nsCOMPtr<nsIAbCollection> mJsIAbCollection;
+  nsCOMPtr<nsIAbItem> mJsIAbItem;
+  nsCOMPtr<nsIInterfaceRequestor> mJsIInterfaceRequestor;
+
+  nsCOMPtr<nsISupports> mJsISupports;
+
+  // Class to bypass JS delegates. nsCOMPtr for when we do cycle collection.
+  nsCOMPtr<nsIAbDirectory> mCppBase;
+
+  RefPtr<DelegateList> mDelegateList;
+  nsDataHashtable<nsCStringHashKey, bool>* mMethods;
+
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+#endif
diff --git a/mailnews/jsaccount/src/JaCompose.cpp b/mailnews/jsaccount/src/JaCompose.cpp
new file mode 100644
index 000000000..a6c1d59f3
--- /dev/null
+++ b/mailnews/jsaccount/src/JaCompose.cpp
@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JaCompose.h"
+#include "nsISupportsUtils.h"
+#include "nsComponentManagerUtils.h"
+
+// This file specifies the implementation of nsIMsgCompose.idl objects
+// in the JsAccount system.
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS_INHERITED(JaBaseCppCompose,
+                            nsMsgCompose,
+                            nsIInterfaceRequestor)
+
+// nsIInterfaceRequestor implementation
+NS_IMETHODIMP
+JaBaseCppCompose::GetInterface(const nsIID & aIID, void **aSink)
+{
+  return QueryInterface(aIID, aSink);
+}
+
+// Delegator object to bypass JS method override.
+
+JaCppComposeDelegator::JaCppComposeDelegator() {
+  mCppBase = do_QueryInterface(
+      NS_ISUPPORTS_CAST(nsIMsgCompose*, new Super(this)));
+  mMethods = nullptr;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(JaCppComposeDelegator,
+                            JaBaseCppCompose,
+                            msgIOverride)
+
+NS_IMPL_ISUPPORTS(JaCppComposeDelegator::Super,
+                  nsIMsgCompose,
+                  nsIMsgSendListener,
+                  nsIInterfaceRequestor)
+
+NS_IMETHODIMP
+JaCppComposeDelegator::SetMethodsToDelegate(msgIDelegateList* aDelegateList)
+{
+  if (!aDelegateList)
+  {
+    NS_WARNING("Null delegate list");
+    return NS_ERROR_NULL_POINTER;
+  }
+  // We static_cast since we want to use the hash object directly.
+  mDelegateList = static_cast<DelegateList*> (aDelegateList);
+  mMethods = &(mDelegateList->mMethods);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppComposeDelegator::GetMethodsToDelegate(msgIDelegateList** aDelegateList)
+{
+  if (!mDelegateList)
+    mDelegateList = new DelegateList("mozilla::mailnews::JaCppComposeDelegator::");
+  mMethods = &(mDelegateList->mMethods);
+  NS_ADDREF(*aDelegateList = mDelegateList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+JaCppComposeDelegator::SetJsDelegate(nsISupports* aJsDelegate)
+{
+  // If these QIs fail, then overrides are not provided for methods in that
+  // interface, which is OK.
+  mJsISupports = aJsDelegate;
+  mJsIMsgCompose = do_QueryInterface(aJsDelegate);
+  mJsIMsgSendListener = do_QueryInterface(aJsDelegate);
+  mJsIInterfaceRequestor = do_QueryInterface(aJsDelegate);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppComposeDelegator::GetJsDelegate(nsISupports **aJsDelegate)
+{
+  NS_ENSURE_ARG_POINTER(aJsDelegate);
+  if (mJsISupports)
+  {
+    NS_ADDREF(*aJsDelegate = mJsISupports);
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP
+JaCppComposeDelegator::GetCppBase(nsISupports** aCppBase)
+{
+  nsCOMPtr<nsISupports> cppBaseSupports;
+  cppBaseSupports = NS_ISUPPORTS_CAST(nsIMsgCompose*, mCppBase);
+  NS_ENSURE_STATE(cppBaseSupports);
+  cppBaseSupports.forget(aCppBase);
+
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/JaCompose.h b/mailnews/jsaccount/src/JaCompose.h
new file mode 100644
index 000000000..b81adda5c
--- /dev/null
+++ b/mailnews/jsaccount/src/JaCompose.h
@@ -0,0 +1,92 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _JaCompose_H_
+#define _JaCompose_H_
+
+#include "DelegateList.h"
+#include "msgIOverride.h"
+#include "nsMsgCompose.h"
+#include "nsAutoPtr.h"
+#include "nsDataHashtable.h"
+#include "nsIInterfaceRequestor.h"
+
+// This file specifies the definition of nsIMsgCompose.idl objects
+// in the JsAccount system.
+
+namespace mozilla {
+namespace mailnews {
+
+/* Header file */
+
+// This class is an XPCOM component, usable in JS, that calls the methods
+// in the C++ base class (bypassing any JS override).
+class JaBaseCppCompose : public nsMsgCompose,
+                                public nsIInterfaceRequestor
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIINTERFACEREQUESTOR
+  JaBaseCppCompose() { }
+
+protected:
+  virtual ~JaBaseCppCompose() { }
+
+};
+
+class JaCppComposeDelegator : public JaBaseCppCompose,
+                                     public msgIOverride
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_MSGIOVERRIDE
+
+  NS_FORWARD_NSIMSGCOMPOSE(DELEGATE_JS(nsIMsgCompose, mJsIMsgCompose)->)
+  NS_FORWARD_NSIMSGSENDLISTENER(DELEGATE_JS(nsIMsgSendListener, mJsIMsgSendListener)->)
+  NS_FORWARD_NSIINTERFACEREQUESTOR(DELEGATE_JS(nsIInterfaceRequestor, mJsIInterfaceRequestor)->)
+
+  JaCppComposeDelegator();
+
+private:
+  virtual ~JaCppComposeDelegator() {
+  }
+
+  // This class will call a method on the delegator, but force the use of the
+  // C++ cppBase class, bypassing any JS Delegate.
+  class Super : public nsIMsgCompose,
+                public nsIInterfaceRequestor
+  {
+    public:
+      Super(JaCppComposeDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      NS_DECL_ISUPPORTS
+      // Forward all overridable methods, bypassing JS override.
+      NS_FORWARD_NSIMSGCOMPOSE(mFakeThis->JaBaseCppCompose::)
+      NS_FORWARD_NSIMSGSENDLISTENER(mFakeThis->JaBaseCppCompose::)
+      NS_FORWARD_NSIINTERFACEREQUESTOR(mFakeThis->JaBaseCppCompose::)
+    private:
+      virtual ~Super() {};
+      JaCppComposeDelegator* mFakeThis;
+  };
+
+  // Interfaces that may be overridden by JS.
+  nsCOMPtr<nsIMsgCompose> mJsIMsgCompose;
+  nsCOMPtr<nsIMsgSendListener> mJsIMsgSendListener;
+  nsCOMPtr<nsIInterfaceRequestor> mJsIInterfaceRequestor;
+
+  nsCOMPtr<nsISupports> mJsISupports;
+
+  // Class to bypass JS delegates.
+  nsCOMPtr<nsIMsgCompose> mCppBase;
+
+  RefPtr<DelegateList> mDelegateList;
+  nsDataHashtable<nsCStringHashKey, bool>* mMethods;
+
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+#endif
diff --git a/mailnews/jsaccount/src/JaIncomingServer.cpp b/mailnews/jsaccount/src/JaIncomingServer.cpp
new file mode 100644
index 000000000..74296ac06
--- /dev/null
+++ b/mailnews/jsaccount/src/JaIncomingServer.cpp
@@ -0,0 +1,109 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JaIncomingServer.h"
+#include "nsISupportsUtils.h"
+#include "nsComponentManagerUtils.h"
+
+// This file specifies the implementation of nsIMsgIncomingServer.idl objects
+// in the JsAccount system.
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS_INHERITED(JaBaseCppIncomingServer,
+                            nsMsgIncomingServer,
+                            nsIInterfaceRequestor)
+
+// nsMsgIncomingServer overrides
+nsresult
+JaBaseCppIncomingServer::CreateRootFolderFromUri(const nsCString &serverUri,
+                                         nsIMsgFolder **rootFolder)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// nsIInterfaceRequestor implementation
+NS_IMETHODIMP
+JaBaseCppIncomingServer::GetInterface(const nsIID & aIID, void **aSink)
+{
+  return QueryInterface(aIID, aSink);
+}
+
+// Delegator object to bypass JS method override.
+
+JaCppIncomingServerDelegator::JaCppIncomingServerDelegator() {
+  mCppBase = do_QueryInterface(
+      NS_ISUPPORTS_CAST(nsIMsgIncomingServer*, new Super(this)));
+  mMethods = nullptr;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(JaCppIncomingServerDelegator,
+                            JaBaseCppIncomingServer,
+                            msgIOverride)
+
+NS_IMPL_ISUPPORTS(JaCppIncomingServerDelegator::Super,
+                  nsIMsgIncomingServer,
+                  nsIInterfaceRequestor)
+
+NS_IMETHODIMP
+JaCppIncomingServerDelegator::SetMethodsToDelegate(msgIDelegateList* aDelegateList)
+{
+  if (!aDelegateList)
+  {
+    NS_WARNING("Null delegate list");
+    return NS_ERROR_NULL_POINTER;
+  }
+  // We static_cast since we want to use the hash object directly.
+  mDelegateList = static_cast<DelegateList*> (aDelegateList);
+  mMethods = &(mDelegateList->mMethods);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppIncomingServerDelegator::GetMethodsToDelegate(msgIDelegateList** aDelegateList)
+{
+  if (!mDelegateList)
+    mDelegateList = new DelegateList("mozilla::mailnews::JaCppIncomingServerDelegator::");
+  mMethods = &(mDelegateList->mMethods);
+  NS_ADDREF(*aDelegateList = mDelegateList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+JaCppIncomingServerDelegator::SetJsDelegate(nsISupports* aJsDelegate)
+{
+  // If these QIs fail, then overrides are not provided for methods in that
+  // interface, which is OK.
+  mJsISupports = aJsDelegate;
+  mJsIMsgIncomingServer = do_QueryInterface(aJsDelegate);
+  mJsIInterfaceRequestor = do_QueryInterface(aJsDelegate);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppIncomingServerDelegator::GetJsDelegate(nsISupports **aJsDelegate)
+{
+  NS_ENSURE_ARG_POINTER(aJsDelegate);
+  if (mJsISupports)
+  {
+    NS_ADDREF(*aJsDelegate = mJsISupports);
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP
+JaCppIncomingServerDelegator::GetCppBase(nsISupports** aCppBase)
+{
+  nsCOMPtr<nsISupports> cppBaseSupports;
+  cppBaseSupports = NS_ISUPPORTS_CAST(nsIMsgIncomingServer*, mCppBase);
+  NS_ENSURE_STATE(cppBaseSupports);
+  cppBaseSupports.forget(aCppBase);
+
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/JaIncomingServer.h b/mailnews/jsaccount/src/JaIncomingServer.h
new file mode 100644
index 000000000..5b0362324
--- /dev/null
+++ b/mailnews/jsaccount/src/JaIncomingServer.h
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _JaIncomingServer_H_
+#define _JaIncomingServer_H_
+
+#include "DelegateList.h"
+#include "msgIOverride.h"
+#include "nsMsgIncomingServer.h"
+#include "nsAutoPtr.h"
+#include "nsDataHashtable.h"
+#include "nsIInterfaceRequestor.h"
+
+// This file specifies the definition of nsIMsgIncomingServer.idl objects
+// in the JsAccount system.
+
+namespace mozilla {
+namespace mailnews {
+
+/* Header file */
+
+// This class is an XPCOM component, usable in JS, that calls the methods
+// in the C++ base class (bypassing any JS override).
+class JaBaseCppIncomingServer : public nsMsgIncomingServer,
+                                public nsIInterfaceRequestor
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIINTERFACEREQUESTOR
+  JaBaseCppIncomingServer() { }
+
+  // nsMsgIncomingServer overrides
+  nsresult CreateRootFolderFromUri(const nsCString &serverUri,
+                                         nsIMsgFolder **rootFolder) override;
+
+protected:
+  virtual ~JaBaseCppIncomingServer() { }
+
+};
+
+class JaCppIncomingServerDelegator : public JaBaseCppIncomingServer,
+                                     public msgIOverride
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_MSGIOVERRIDE
+
+  NS_FORWARD_NSIMSGINCOMINGSERVER(DELEGATE_JS(nsIMsgIncomingServer, mJsIMsgIncomingServer)->)
+  NS_FORWARD_NSIINTERFACEREQUESTOR(DELEGATE_JS(nsIInterfaceRequestor, mJsIInterfaceRequestor)->)
+
+  JaCppIncomingServerDelegator();
+
+private:
+  virtual ~JaCppIncomingServerDelegator() {
+  }
+
+  // This class will call a method on the delegator, but force the use of the
+  // C++ parent class, bypassing any JS Delegate.
+  class Super : public nsIMsgIncomingServer,
+                public nsIInterfaceRequestor
+  {
+    public:
+      Super(JaCppIncomingServerDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      NS_DECL_ISUPPORTS
+      // Forward all overridable methods, bypassing JS override.
+      NS_FORWARD_NSIMSGINCOMINGSERVER(mFakeThis->JaBaseCppIncomingServer::)
+      NS_FORWARD_NSIINTERFACEREQUESTOR(mFakeThis->JaBaseCppIncomingServer::)
+    private:
+      virtual ~Super() {};
+      JaCppIncomingServerDelegator* mFakeThis;
+  };
+
+  // Interfaces that may be overridden by JS.
+  nsCOMPtr<nsIMsgIncomingServer> mJsIMsgIncomingServer;
+  nsCOMPtr<nsIInterfaceRequestor> mJsIInterfaceRequestor;
+
+  nsCOMPtr<nsISupports> mJsISupports;
+
+  // Class to bypass JS delegates.
+  nsCOMPtr<nsIMsgIncomingServer> mCppBase;
+
+  RefPtr<DelegateList> mDelegateList;
+  nsDataHashtable<nsCStringHashKey, bool>* mMethods;
+
+
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+#endif
diff --git a/mailnews/jsaccount/src/JaMsgFolder.cpp b/mailnews/jsaccount/src/JaMsgFolder.cpp
new file mode 100644
index 000000000..e51528e11
--- /dev/null
+++ b/mailnews/jsaccount/src/JaMsgFolder.cpp
@@ -0,0 +1,207 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JaMsgFolder.h"
+#include "nsISupportsUtils.h"
+#include "nsMsgBaseCID.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIUUIDGenerator.h"
+#include "nsIComponentRegistrar.h"
+#include "nsMsgDBCID.h"
+
+#define MAILDATABASE_CONTRACTID_BASE "@mozilla.org/nsMsgDatabase/msgDB-"
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS_INHERITED(JaBaseCppMsgFolder, nsMsgDBFolder,
+                            nsIInterfaceRequestor)
+
+// nsIInterfaceRequestor implementation
+NS_IMETHODIMP
+JaBaseCppMsgFolder::GetInterface(const nsIID & aIID, void **aSink)
+{
+  return QueryInterface(aIID, aSink);
+}
+
+// Definition of abstract nsMsgDBFolder methods.
+nsresult
+JaBaseCppMsgFolder::GetDatabase()
+{
+  nsresult rv = NS_OK;
+  if (!mDatabase)
+  {
+
+    nsCOMPtr<nsIMsgDBService> msgDBService = do_GetService(NS_MSGDB_SERVICE_CONTRACTID, &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // Create the database, keeping it if it is "out of date"
+    rv = msgDBService->OpenFolderDB(this, true, getter_AddRefs(mDatabase));
+    if (rv == NS_MSG_ERROR_FOLDER_SUMMARY_MISSING)
+    {
+      rv = msgDBService->CreateNewDB(this, getter_AddRefs(mDatabase));
+      NS_ENSURE_STATE(mDatabase);
+      // not sure about this ... the issue is that if the summary is not valid, then
+      //  the db does not get added to the cache in the future, and reindexes
+      //  do not show all of the messages.
+      //mDatabase->SetSummaryValid(true);
+      mDatabase->SetSummaryValid(false);
+      CreateDummyFile(this);
+    }
+
+    if (rv != NS_MSG_ERROR_FOLDER_SUMMARY_OUT_OF_DATE)
+      NS_ENSURE_SUCCESS(rv, rv);
+    else if (mDatabase)
+    {
+      // Not going to warn here, because on initialization we set all
+      //  databases as invalid.
+      //NS_WARNING("Mail Summary database is out of date");
+      // Grrr, the only way to get this into the cache is to set the db as valid,
+      //  close, reopen, then set as invalid.
+      mDatabase->SetSummaryValid(true);
+      msgDBService->ForceFolderDBClosed(this);
+      rv = msgDBService->OpenFolderDB(this, true, getter_AddRefs(mDatabase));
+      if (mDatabase)
+        mDatabase->SetSummaryValid(false);
+    }
+
+    if (mDatabase)
+    {
+      //
+      // When I inadvertently deleted the out-of-date database, I hit this code with
+      //  the db's m_dbFolderInfo as null from the delete, yet the local mDatabase
+      //  reference kept the database alive. So I hit an assert when I tried to open
+      //  the database. Be careful if you try to fix the out-of-date issues!
+      //
+      //UpdateNewMessages();
+      if(mAddListener)
+        mDatabase->AddListener(this);
+      // UpdateSummaryTotals can null mDatabase during initialization, so we save a local copy
+      nsCOMPtr<nsIMsgDatabase> database(mDatabase);
+      UpdateSummaryTotals(true);
+      mDatabase = database;
+
+    }
+  }
+
+  return rv;
+}
+
+/*
+ * The utility function GetSummaryFileLocation takes a folder file,
+ *  then appends .msf to come up with the name of the database file. So
+ *  we need a placeholder file with simply the folder name. This method
+ *  creates an appropriate file as a placeholder, or you may use the file if
+ *  appropriate.
+ */
+nsresult
+JaBaseCppMsgFolder::CreateDummyFile(nsIMsgFolder* aMailFolder)
+{
+  nsresult rv;
+  if (!aMailFolder)
+    return NS_OK;
+  nsCOMPtr <nsIFile> path;
+  // need to make sure folder exists...
+  aMailFolder->GetFilePath(getter_AddRefs(path));
+  if (path)
+  {
+    bool exists;
+    rv = path->Exists(&exists);
+    if (!exists)
+    {
+      rv = path->Create(nsIFile::NORMAL_FILE_TYPE, 0644);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+  return NS_OK;
+}
+
+// AFAICT this is unused in mailnews code.
+nsresult
+JaBaseCppMsgFolder::CreateChildFromURI(const nsCString &uri, nsIMsgFolder **folder)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// Delegator object to bypass JS method override.
+
+JaCppMsgFolderDelegator::JaCppMsgFolderDelegator() :
+  mCppBase(new Super(this)),
+  mMethods(nullptr)
+{ }
+
+NS_IMPL_ISUPPORTS_INHERITED(JaCppMsgFolderDelegator, JaBaseCppMsgFolder,
+                            msgIOverride)
+
+NS_IMPL_ISUPPORTS(JaCppMsgFolderDelegator::Super,
+                  nsIMsgFolder,
+                  nsIRDFResource,
+                  nsIRDFNode,
+                  nsIDBChangeListener,
+                  nsIUrlListener,
+                  nsIJunkMailClassificationListener,
+                  nsIMsgTraitClassificationListener,
+                  nsIInterfaceRequestor)
+
+NS_IMETHODIMP
+JaCppMsgFolderDelegator::SetMethodsToDelegate(msgIDelegateList* aDelegateList)
+{
+  if (!aDelegateList)
+  {
+    NS_WARNING("Null delegate list");
+    return NS_ERROR_NULL_POINTER;
+  }
+  // We static_cast since we want to use the hash object directly.
+  mDelegateList = static_cast<DelegateList*> (aDelegateList);
+  mMethods = &(mDelegateList->mMethods);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppMsgFolderDelegator::GetMethodsToDelegate(msgIDelegateList** aDelegateList)
+{
+  if (!mDelegateList)
+    mDelegateList = new DelegateList("mozilla::mailnews::JaCppMsgFolderDelegator::");
+  mMethods = &(mDelegateList->mMethods);
+  NS_ADDREF(*aDelegateList = mDelegateList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaCppMsgFolderDelegator::SetJsDelegate(nsISupports* aJsDelegate)
+{
+  // If these QIs fail, then overrides are not provided for methods in that
+  // interface, which is OK.
+  mJsISupports = aJsDelegate;
+  mJsIMsgFolder = do_QueryInterface(aJsDelegate);
+  mJsIDBChangeListener = do_QueryInterface(aJsDelegate);
+  mJsIUrlListener = do_QueryInterface(aJsDelegate);
+  mJsIJunkMailClassificationListener = do_QueryInterface(aJsDelegate);
+  mJsIMsgTraitClassificationListener = do_QueryInterface(aJsDelegate);
+  mJsIInterfaceRequestor = do_QueryInterface(aJsDelegate);
+  return NS_OK;
+}
+NS_IMETHODIMP JaCppMsgFolderDelegator::GetJsDelegate(nsISupports **aJsDelegate)
+{
+  NS_ENSURE_ARG_POINTER(aJsDelegate);
+  if (mJsISupports)
+  {
+    NS_ADDREF(*aJsDelegate = mJsISupports);
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP JaCppMsgFolderDelegator::GetCppBase(nsISupports** aCppBase)
+{
+  nsCOMPtr<nsISupports> cppBaseSupports;
+  cppBaseSupports = NS_ISUPPORTS_CAST(nsIMsgFolder*, mCppBase);
+  NS_ENSURE_STATE(cppBaseSupports);
+  cppBaseSupports.forget(aCppBase);
+
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/JaMsgFolder.h b/mailnews/jsaccount/src/JaMsgFolder.h
new file mode 100644
index 000000000..514d6e07f
--- /dev/null
+++ b/mailnews/jsaccount/src/JaMsgFolder.h
@@ -0,0 +1,126 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _JaMsgFolder_H_
+#define _JaMsgFolder_H_
+
+#include "DelegateList.h"
+#include "msgIOverride.h"
+#include "nsMsgDBFolder.h"
+#include "nsAutoPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsDataHashtable.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsWeakReference.h"
+#include "nsNetUtil.h"
+
+namespace mozilla {
+namespace mailnews {
+
+/* Header file */
+
+// This class is an XPCOM component, usable in JS, that calls the methods
+// in the C++ base class (bypassing any JS override).
+class JaBaseCppMsgFolder : public nsMsgDBFolder,
+                           public nsIInterfaceRequestor
+
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIINTERFACEREQUESTOR
+  JaBaseCppMsgFolder() { }
+
+  // nsMsgDBFolder overrides
+
+  nsresult CreateChildFromURI(const nsCString &uri, nsIMsgFolder **folder) override;
+  nsresult GetDatabase() override;
+
+  // Local Utility Functions
+
+  // Create a placeholder file to represent a folder.
+  nsresult CreateDummyFile(nsIMsgFolder* aMailFolder);
+
+protected:
+  virtual ~JaBaseCppMsgFolder() { }
+
+};
+
+class JaCppMsgFolderDelegator : public JaBaseCppMsgFolder,
+                                public msgIOverride
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_MSGIOVERRIDE
+
+  // Note that we do not support override of RDF methods.
+  NS_FORWARD_NSIRDFRESOURCE(JaBaseCppMsgFolder::)
+  NS_FORWARD_NSIRDFNODE(JaBaseCppMsgFolder::)
+  NS_FORWARD_NSIMSGFOLDER(DELEGATE_JS(nsIMsgFolder, mJsIMsgFolder)->)
+  NS_FORWARD_NSIDBCHANGELISTENER(
+    DELEGATE_JS(nsIDBChangeListener, mJsIDBChangeListener)->)
+  NS_FORWARD_NSIURLLISTENER(DELEGATE_JS(nsIUrlListener, mJsIUrlListener)->)
+  NS_FORWARD_NSIJUNKMAILCLASSIFICATIONLISTENER(
+      DELEGATE_JS(nsIJunkMailClassificationListener,
+                  mJsIJunkMailClassificationListener)->)
+  NS_FORWARD_NSIMSGTRAITCLASSIFICATIONLISTENER(
+      DELEGATE_JS(nsIMsgTraitClassificationListener,
+                  mJsIMsgTraitClassificationListener)->)
+  NS_FORWARD_NSIINTERFACEREQUESTOR(
+      DELEGATE_JS(nsIInterfaceRequestor, mJsIInterfaceRequestor)->)
+
+  JaCppMsgFolderDelegator();
+
+private:
+  virtual ~JaCppMsgFolderDelegator() {
+  }
+
+  class Super : public nsIMsgFolder,
+                public nsIRDFResource,
+                public nsIDBChangeListener,
+                public nsIUrlListener,
+                public nsIJunkMailClassificationListener,
+                public nsIMsgTraitClassificationListener,
+                public nsIInterfaceRequestor
+  {
+    public:
+      // Why fake this? Because this method is fully owned by
+      // JaCppMsgFolderDelegator, and this reference is to the "this" of the
+      // main method. But it is not really the local "this".
+      Super(JaCppMsgFolderDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      NS_DECL_ISUPPORTS
+      NS_FORWARD_NSIMSGFOLDER(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIRDFRESOURCE(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIRDFNODE(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIDBCHANGELISTENER(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIURLLISTENER(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIJUNKMAILCLASSIFICATIONLISTENER(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIMSGTRAITCLASSIFICATIONLISTENER(mFakeThis->JaBaseCppMsgFolder::)
+      NS_FORWARD_NSIINTERFACEREQUESTOR(mFakeThis->JaBaseCppMsgFolder::)
+    private:
+      virtual ~Super() {}
+      JaCppMsgFolderDelegator* mFakeThis;
+  };
+
+  // Interfaces that may be overridden by JS.
+  nsCOMPtr<nsIMsgFolder> mJsIMsgFolder;
+  nsCOMPtr<nsIDBChangeListener> mJsIDBChangeListener;
+  nsCOMPtr<nsIUrlListener> mJsIUrlListener;
+  nsCOMPtr<nsIJunkMailClassificationListener> mJsIJunkMailClassificationListener;
+  nsCOMPtr<nsIMsgTraitClassificationListener> mJsIMsgTraitClassificationListener;
+  nsCOMPtr<nsIInterfaceRequestor> mJsIInterfaceRequestor;
+
+  nsCOMPtr<nsISupports> mJsISupports;
+
+  nsCOMPtr<nsIMsgFolder> mCppBase;
+  RefPtr<DelegateList> mDelegateList;
+  nsDataHashtable<nsCStringHashKey, bool>* mMethods;
+
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+#endif
diff --git a/mailnews/jsaccount/src/JaSend.cpp b/mailnews/jsaccount/src/JaSend.cpp
new file mode 100644
index 000000000..5a473d2f8
--- /dev/null
+++ b/mailnews/jsaccount/src/JaSend.cpp
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JaSend.h"
+#include "nsISupportsUtils.h"
+#include "nsComponentManagerUtils.h"
+
+// This file specifies the implementation of nsIMsgSend.idl objects
+// in the JsAccount system.
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS_INHERITED(JaBaseCppSend,
+                            nsMsgComposeAndSend,
+                            nsIInterfaceRequestor)
+
+// nsIInterfaceRequestor implementation
+NS_IMETHODIMP
+JaBaseCppSend::GetInterface(const nsIID & aIID, void **aSink)
+{
+  return QueryInterface(aIID, aSink);
+}
+
+// Delegator object to bypass JS method override.
+
+JaCppSendDelegator::JaCppSendDelegator() {
+  mCppBase = do_QueryInterface(
+      NS_ISUPPORTS_CAST(nsIMsgSend*, new Super(this)));
+  mMethods = nullptr;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(JaCppSendDelegator,
+                            JaBaseCppSend,
+                            msgIOverride)
+
+NS_IMPL_ISUPPORTS(JaCppSendDelegator::Super,
+                  nsIMsgSend,
+                  nsIMsgOperationListener,
+                  nsIInterfaceRequestor)
+
+NS_IMETHODIMP
+JaCppSendDelegator::SetMethodsToDelegate(msgIDelegateList* aDelegateList)
+{
+  if (!aDelegateList)
+  {
+    NS_WARNING("Null delegate list");
+    return NS_ERROR_NULL_POINTER;
+  }
+  // We static_cast since we want to use the hash object directly.
+  mDelegateList = static_cast<DelegateList*> (aDelegateList);
+  mMethods = &(mDelegateList->mMethods);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppSendDelegator::GetMethodsToDelegate(msgIDelegateList** aDelegateList)
+{
+  if (!mDelegateList)
+    mDelegateList = new DelegateList("mozilla::mailnews::JaCppSendDelegator::");
+  mMethods = &(mDelegateList->mMethods);
+  NS_ADDREF(*aDelegateList = mDelegateList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+JaCppSendDelegator::SetJsDelegate(nsISupports* aJsDelegate)
+{
+  // If these QIs fail, then overrides are not provided for methods in that
+  // interface, which is OK.
+  mJsISupports = aJsDelegate;
+  mJsIMsgSend = do_QueryInterface(aJsDelegate);
+  mJsIInterfaceRequestor = do_QueryInterface(aJsDelegate);
+  return NS_OK;
+}
+NS_IMETHODIMP
+JaCppSendDelegator::GetJsDelegate(nsISupports **aJsDelegate)
+{
+  NS_ENSURE_ARG_POINTER(aJsDelegate);
+  if (mJsISupports)
+  {
+    NS_ADDREF(*aJsDelegate = mJsISupports);
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP
+JaCppSendDelegator::GetCppBase(nsISupports** aCppBase)
+{
+  nsCOMPtr<nsISupports> cppBaseSupports;
+  cppBaseSupports = NS_ISUPPORTS_CAST(nsIMsgSend*, mCppBase);
+  NS_ENSURE_STATE(cppBaseSupports);
+  cppBaseSupports.forget(aCppBase);
+
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/JaSend.h b/mailnews/jsaccount/src/JaSend.h
new file mode 100644
index 000000000..c4d8ac3b8
--- /dev/null
+++ b/mailnews/jsaccount/src/JaSend.h
@@ -0,0 +1,96 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _JaSend_H_
+#define _JaSend_H_
+
+#include "DelegateList.h"
+#include "msgIOverride.h"
+#include "nsMsgSend.h"
+#include "nsAutoPtr.h"
+#include "nsDataHashtable.h"
+#include "nsIInterfaceRequestor.h"
+
+// This file specifies the definition of nsIMsgSend.idl objects
+// in the JsAccount system.
+
+namespace mozilla {
+namespace mailnews {
+
+/* Header file */
+
+// This class is an XPCOM component, usable in JS, that calls the methods
+// in the C++ base class (bypassing any JS override).
+class JaBaseCppSend : public nsMsgComposeAndSend,
+                      public nsIInterfaceRequestor
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIINTERFACEREQUESTOR
+  JaBaseCppSend() { }
+
+protected:
+  virtual ~JaBaseCppSend() { }
+
+};
+
+class JaCppSendDelegator : public JaBaseCppSend,
+                           public msgIOverride
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_MSGIOVERRIDE
+
+  NS_FORWARD_NSIMSGSEND(DELEGATE_JS(nsIMsgSend, mJsIMsgSend)->)
+  NS_FORWARD_NSIMSGOPERATIONLISTENER(
+      DELEGATE_JS(nsIMsgOperationListener, mJsIMsgOperationListener)->)
+  NS_FORWARD_NSIINTERFACEREQUESTOR(
+      DELEGATE_JS(nsIInterfaceRequestor, mJsIInterfaceRequestor)->)
+
+  JaCppSendDelegator();
+
+private:
+  virtual ~JaCppSendDelegator() {
+  }
+
+  // This class will call a method on the delegator, but force the use of the
+  // C++ parent class, bypassing any JS Delegate.
+  class Super : public nsIMsgSend,
+                public nsIMsgOperationListener,
+                public nsIInterfaceRequestor
+  {
+    public:
+      Super(JaCppSendDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      NS_DECL_ISUPPORTS
+      // Forward all overridable methods, bypassing JS override.
+      NS_FORWARD_NSIMSGSEND(mFakeThis->JaBaseCppSend::)
+      NS_FORWARD_NSIMSGOPERATIONLISTENER(mFakeThis->JaBaseCppSend::)
+      NS_FORWARD_NSIINTERFACEREQUESTOR(mFakeThis->JaBaseCppSend::)
+    private:
+      virtual ~Super() {};
+      JaCppSendDelegator* mFakeThis;
+  };
+
+  // Interfaces that may be overridden by JS.
+  nsCOMPtr<nsIMsgSend> mJsIMsgSend;
+  nsCOMPtr<nsIMsgOperationListener> mJsIMsgOperationListener;
+  nsCOMPtr<nsIInterfaceRequestor> mJsIInterfaceRequestor;
+
+  nsCOMPtr<nsISupports> mJsISupports;
+
+  // Class to bypass JS delegates.
+  nsCOMPtr<nsIMsgSend> mCppBase;
+
+  RefPtr<DelegateList> mDelegateList;
+  nsDataHashtable<nsCStringHashKey, bool>* mMethods;
+
+
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+#endif
diff --git a/mailnews/jsaccount/src/JaUrl.cpp b/mailnews/jsaccount/src/JaUrl.cpp
new file mode 100644
index 000000000..70b19329c
--- /dev/null
+++ b/mailnews/jsaccount/src/JaUrl.cpp
@@ -0,0 +1,230 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JaUrl.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIFile.h"
+#include "nsIMessenger.h"
+#include "nsIMsgHdr.h"
+#include "nsISupportsUtils.h"
+#include "nsMsgBaseCID.h"
+#include "nsMsgUtils.h"
+
+// This file contains an implementation of mailnews URLs in JsAccount.
+
+namespace mozilla {
+namespace mailnews {
+
+NS_IMPL_ISUPPORTS_INHERITED(JaBaseCppUrl, nsMsgMailNewsUrl,
+                            nsIMsgMessageUrl,
+                            nsIInterfaceRequestor,
+                            nsISupportsWeakReference)
+
+// nsIMsgMailNewsUrl overrides
+NS_IMETHODIMP JaBaseCppUrl::GetFolder(nsIMsgFolder **aFolder)
+{
+  NS_ENSURE_ARG_POINTER(aFolder);
+  NS_IF_ADDREF(*aFolder = mFolder);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::SetFolder(nsIMsgFolder *aFolder)
+{
+  mFolder = aFolder;
+  return NS_OK;
+}
+
+// nsIMsgMessageUrl implementation
+NS_IMETHODIMP JaBaseCppUrl::GetUri(char **aUri)
+{
+  if (!mUri.IsEmpty())
+    *aUri = ToNewCString(mUri);
+  else
+    return NS_ERROR_NOT_INITIALIZED;
+  return NS_OK;
+}
+NS_IMETHODIMP JaBaseCppUrl::SetUri(const char *aUri)
+{
+  mUri = aUri;
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::GetMessageFile(nsIFile **aMessageFile)
+{
+  NS_ENSURE_ARG_POINTER(aMessageFile);
+  NS_IF_ADDREF(*aMessageFile = mMessageFile);
+  return NS_OK;
+}
+NS_IMETHODIMP JaBaseCppUrl::SetMessageFile(nsIFile *aMessageFile)
+{
+  mMessageFile = aMessageFile;
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::GetAddDummyEnvelope(bool *aAddDummyEnvelope)
+{
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+NS_IMETHODIMP JaBaseCppUrl::SetAddDummyEnvelope(bool aAddDummyEnvelope)
+{
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::GetCanonicalLineEnding(bool *aCanonicalLineEnding)
+{
+  NS_ENSURE_ARG_POINTER(aCanonicalLineEnding);
+  *aCanonicalLineEnding = mCanonicalLineEnding;
+  return NS_OK;
+}
+NS_IMETHODIMP JaBaseCppUrl::SetCanonicalLineEnding(bool aCanonicalLineEnding)
+{
+  mCanonicalLineEnding = aCanonicalLineEnding;
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::GetOriginalSpec(char **aOriginalSpec)
+{
+  if (!aOriginalSpec || mOriginalSpec.IsEmpty())
+    return NS_ERROR_NULL_POINTER;
+  *aOriginalSpec = ToNewCString(mOriginalSpec);
+  return NS_OK;
+}
+NS_IMETHODIMP JaBaseCppUrl::SetOriginalSpec(const char *aOriginalSpec)
+{
+  mOriginalSpec = aOriginalSpec;
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::GetPrincipalSpec(nsACString& aPrincipalSpec)
+{
+  // URLs contain a lot of query parts. We want need a normalised form:
+  // scheme://server/folder?number=123
+  nsCOMPtr<nsIMsgMailNewsUrl> mailnewsURL;
+  QueryInterface(NS_GET_IID(nsIMsgMailNewsUrl), getter_AddRefs(mailnewsURL));
+
+  nsAutoCString spec;
+  mailnewsURL->GetSpecIgnoringRef(spec);
+
+  nsAutoCString queryPart = MsgExtractQueryPart(spec, "number=");
+
+  // Strip any query part beginning with ? or /;
+  int32_t ind = spec.Find("/;");
+  if (ind != kNotFound)
+    spec.SetLength(ind);
+
+  ind = spec.FindChar('?');
+  if (ind != kNotFound)
+    spec.SetLength(ind);
+
+  if (!queryPart.IsEmpty())
+    spec += NS_LITERAL_CSTRING("?") + queryPart;
+
+  aPrincipalSpec.Assign(spec);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::GetMessageHeader(nsIMsgDBHdr **aMessageHeader)
+{
+  // This routine does a lookup using messenger, assumming that the message URI
+  // has been set in mUri.
+  NS_ENSURE_TRUE(!mUri.IsEmpty(), NS_ERROR_NOT_INITIALIZED);
+  nsresult rv;
+  nsCOMPtr<nsIMessenger> messenger(do_CreateInstance(NS_MESSENGER_CONTRACTID, &rv));
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  rv = messenger->MsgHdrFromURI(mUri, getter_AddRefs(msgHdr));
+  NS_ENSURE_SUCCESS(rv, rv);
+  msgHdr.forget(aMessageHeader);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaBaseCppUrl::SetMessageHeader(nsIMsgDBHdr *aMsgHdr)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// nsIInterfaceRequestor implementation
+NS_IMETHODIMP JaBaseCppUrl::GetInterface(const nsIID & aIID, void **aSink)
+{
+  return QueryInterface(aIID, aSink);
+}
+
+// Delegator
+NS_IMPL_ISUPPORTS_INHERITED(JaCppUrlDelegator,
+                            JaBaseCppUrl,
+                            msgIOverride)
+
+// Delegator object to bypass JS method override.
+NS_IMPL_ISUPPORTS(JaCppUrlDelegator::Super,
+                  nsIMsgMailNewsUrl,
+                  nsIMsgMessageUrl,
+                  nsIURI,
+                  nsIURIWithQuery,
+                  nsIURL,
+                  nsIInterfaceRequestor)
+
+JaCppUrlDelegator::JaCppUrlDelegator() :
+  mCppBase(new Super(this)),
+  mMethods(nullptr)
+{ }
+
+NS_IMETHODIMP JaCppUrlDelegator::SetMethodsToDelegate(msgIDelegateList *aDelegateList)
+{
+  if (!aDelegateList)
+  {
+    NS_WARNING("Null delegate list");
+    return NS_ERROR_NULL_POINTER;
+  }
+  // We static_cast since we want to use the hash object directly.
+  mDelegateList = static_cast<DelegateList*> (aDelegateList);
+  mMethods = &(mDelegateList->mMethods);
+  return NS_OK;
+}
+NS_IMETHODIMP JaCppUrlDelegator::GetMethodsToDelegate(msgIDelegateList **aDelegateList)
+{
+  if (!mDelegateList)
+    mDelegateList = new DelegateList("mozilla::mailnews::JaCppUrlDelegator::");
+  mMethods = &(mDelegateList->mMethods);
+  NS_ADDREF(*aDelegateList = mDelegateList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JaCppUrlDelegator::SetJsDelegate(nsISupports *aJsDelegate)
+{
+  // If these QIs fail, then overrides are not provided for methods in that
+  // interface, which is OK.
+  mJsISupports = aJsDelegate;
+  mJsIMsgMailNewsUrl = do_QueryInterface(aJsDelegate);
+  mJsIURI = do_QueryInterface(aJsDelegate);
+  mJsIURIWithQuery = do_QueryInterface(aJsDelegate);
+  mJsIURL = do_QueryInterface(aJsDelegate);
+  mJsIMsgMessageUrl = do_QueryInterface(aJsDelegate);
+  mJsIInterfaceRequestor = do_QueryInterface(aJsDelegate);
+  return NS_OK;
+}
+NS_IMETHODIMP JaCppUrlDelegator::GetJsDelegate(nsISupports **aJsDelegate)
+{
+  NS_ENSURE_ARG_POINTER(aJsDelegate);
+  if (mJsISupports)
+  {
+    NS_ADDREF(*aJsDelegate = mJsISupports);
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+NS_IMETHODIMP JaCppUrlDelegator::GetCppBase(nsISupports **aCppBase)
+{
+  nsCOMPtr<nsISupports> cppBaseSupports;
+  cppBaseSupports = NS_ISUPPORTS_CAST(nsIMsgMailNewsUrl*, mCppBase);
+  NS_ENSURE_STATE(cppBaseSupports);
+  cppBaseSupports.forget(aCppBase);
+
+  return NS_OK;
+}
+
+} // namespace mailnews
+} // namespace mozilla
diff --git a/mailnews/jsaccount/src/JaUrl.h b/mailnews/jsaccount/src/JaUrl.h
new file mode 100644
index 000000000..57c902eee
--- /dev/null
+++ b/mailnews/jsaccount/src/JaUrl.h
@@ -0,0 +1,121 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _JaUrl_H_
+#define _JaUrl_H_
+
+#include "DelegateList.h"
+#include "msgCore.h"
+#include "msgIOverride.h"
+#include "nsAutoPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsDataHashtable.h"
+#include "nsIFile.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIMsgFolder.h"
+#include "nsISupports.h"
+#include "nsMsgMailNewsUrl.h"
+#include "nsWeakReference.h"
+
+namespace mozilla {
+namespace mailnews {
+
+/* Header file */
+
+// This class is an XPCOM component, usable in JS, that calls the methods
+// in the C++ base class (bypassing any JS override).
+class JaBaseCppUrl : public nsMsgMailNewsUrl,
+                     public nsIMsgMessageUrl,
+                     public nsIInterfaceRequestor,
+                     public nsSupportsWeakReference
+
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIMSGMESSAGEURL
+  NS_DECL_NSIINTERFACEREQUESTOR
+  JaBaseCppUrl() { }
+
+  // nsIMsgMailNewsUrl overrides
+  NS_IMETHOD GetFolder(nsIMsgFolder **aFolder) override;
+  NS_IMETHOD SetFolder(nsIMsgFolder *aFolder) override;
+
+protected:
+  virtual ~JaBaseCppUrl() { }
+
+  // nsIMsgMailUrl variables.
+
+  nsCOMPtr<nsIMsgFolder> mFolder;
+
+  // nsIMsgMessageUrl variables.
+
+  // the uri for the original message, like ews-message://server/folder#123
+  nsCString mUri;
+  nsCOMPtr<nsIFile> mMessageFile;
+  bool mCanonicalLineEnding;
+  nsCString mOriginalSpec;
+};
+
+class JaCppUrlDelegator : public JaBaseCppUrl,
+                          public msgIOverride
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_MSGIOVERRIDE
+
+  NS_FORWARD_NSIMSGMAILNEWSURL(DELEGATE_JS(nsIMsgMailNewsUrl, mJsIMsgMailNewsUrl)->)
+  NS_FORWARD_NSIURI(DELEGATE_JS(nsIURI, mJsIURI)->)
+  NS_FORWARD_NSIURIWITHQUERY(DELEGATE_JS(nsIURIWithQuery, mJsIURIWithQuery)->)
+  NS_FORWARD_NSIURL(DELEGATE_JS(nsIURL, mJsIURL)->)
+  NS_FORWARD_NSIMSGMESSAGEURL(DELEGATE_JS(nsIMsgMessageUrl, mJsIMsgMessageUrl)->)
+  NS_FORWARD_NSIINTERFACEREQUESTOR(DELEGATE_JS(nsIInterfaceRequestor, mJsIInterfaceRequestor)->)
+
+  JaCppUrlDelegator();
+
+  class Super : public nsIMsgMailNewsUrl,
+                public nsIMsgMessageUrl,
+                public nsIInterfaceRequestor
+  {
+    public:
+      Super(JaCppUrlDelegator *aFakeThis) {mFakeThis = aFakeThis;}
+      NS_DECL_ISUPPORTS
+      NS_FORWARD_NSIMSGMAILNEWSURL(mFakeThis->JaBaseCppUrl::)
+      NS_FORWARD_NSIURI(mFakeThis->JaBaseCppUrl::)
+      NS_FORWARD_NSIURIWITHQUERY(mFakeThis->JaBaseCppUrl::)
+      NS_FORWARD_NSIURL(mFakeThis->JaBaseCppUrl::)
+      NS_FORWARD_NSIMSGMESSAGEURL(mFakeThis->JaBaseCppUrl::)
+      NS_FORWARD_NSIINTERFACEREQUESTOR(mFakeThis->JaBaseCppUrl::)
+    private:
+      virtual ~Super() {}
+      JaCppUrlDelegator *mFakeThis;
+  };
+
+private:
+  virtual ~JaCppUrlDelegator() {
+  }
+
+  // Interfaces that may be overridden by JS.
+  nsCOMPtr<nsIMsgMailNewsUrl> mJsIMsgMailNewsUrl;
+  nsCOMPtr<nsIURI> mJsIURI;
+  nsCOMPtr<nsIURIWithQuery> mJsIURIWithQuery;
+  nsCOMPtr<nsIURL> mJsIURL;
+  nsCOMPtr<nsIMsgMessageUrl> mJsIMsgMessageUrl;
+  nsCOMPtr<nsIInterfaceRequestor> mJsIInterfaceRequestor;
+
+  // Owning reference to the JS override.
+  nsCOMPtr<nsISupports> mJsISupports;
+
+  // Class to bypass JS delegates. nsCOMPtr for when we do cycle collection.
+  nsCOMPtr<nsIMsgMailNewsUrl> mCppBase;
+
+  RefPtr<DelegateList> mDelegateList;
+  nsDataHashtable<nsCStringHashKey, bool> *mMethods;
+};
+
+} // namespace mailnews
+} // namespace mozilla
+
+#endif
diff --git a/mailnews/jsaccount/src/moz.build b/mailnews/jsaccount/src/moz.build
new file mode 100644
index 000000000..761bb04ca
--- /dev/null
+++ b/mailnews/jsaccount/src/moz.build
@@ -0,0 +1,28 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    'DelegateList.cpp',
+    'JaAbDirectory.cpp',
+    'JaCompose.cpp',
+    'JaIncomingServer.cpp',
+    'JaMsgFolder.cpp',
+    'JaSend.cpp',
+    'JaUrl.cpp',
+]
+
+EXPORTS += [
+    'DelegateList.h',
+    'JaAbDirectory.h',
+    'JaCompose.h',
+    'JaIncomingServer.h',
+    'JaMsgFolder.h',
+    'JaSend.h',
+    'JaUrl.h',
+]
+
+Library('JsAccount')
+FINAL_LIBRARY = 'mail'