diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index fdb2541f7603..426d38b23a16 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -237,8 +237,6 @@ pref("browser.startup.homepage",            "about:home");
 // Whether we should skip the homepage when opening the first-run page
 pref("browser.startup.firstrunSkipsHomepage", true);
 
-pref("browser.dedicatedprofile.welcome.accounts.endpoint", "https://accounts.firefox.com/");
-
 // Show an about:blank window as early as possible for quick startup feedback.
 // Held to nightly on Linux due to bug 1450626.
 // Disabled on Mac because the bouncing dock icon already provides feedback.
diff --git a/browser/base/content/newInstallPage.js b/browser/base/content/newInstallPage.js
index 11b78470e3db..c2d86eafc1e1 100644
--- a/browser/base/content/newInstallPage.js
+++ b/browser/base/content/newInstallPage.js
@@ -2,12 +2,13 @@
  * 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/. */
 
+/* global RPMGetUpdateChannel, RPMGetFxAccountsEndpoint */
+
 const PARAMS = new URL(location).searchParams;
 const ENTRYPOINT = "new-install-page";
-const SOURCE = `new-install-page-${PARAMS.get("channel")}`;
+const SOURCE = `new-install-page-${RPMGetUpdateChannel()}`;
 const CAMPAIGN = "dedicated-profiles";
 const ENDPOINT = PARAMS.get("endpoint");
-const CONTEXT = "fx_desktop_v3";
 
 function appendAccountsParams(url) {
   url.searchParams.set("entrypoint", ENTRYPOINT);
@@ -24,7 +25,8 @@ function appendParams(url, params) {
 }
 
 async function requestFlowMetrics() {
-  let requestURL = new URL(`${ENDPOINT}metrics-flow`);
+  let requestURL = new URL(await endpoint);
+  requestURL.pathname = "metrics-flow";
   appendParams(requestURL, {
     "form_type": "email",
   });
@@ -47,11 +49,9 @@ async function submitForm(event) {
 
   let { flowId, flowBeginTime } = await metrics;
 
-  let requestURL = new URL(ENDPOINT);
+  let requestURL = new URL(await endpoint);
   appendParams(requestURL, {
-    "service": "sync",
     "action": "email",
-    "context": CONTEXT,
     "utm_campaign": CAMPAIGN,
     "email": input.value,
     "flow_id": flowId,
@@ -61,6 +61,8 @@ async function submitForm(event) {
   window.open(requestURL, "_blank", "noopener");
 }
 
+const endpoint = RPMGetFxAccountsEndpoint(ENTRYPOINT);
+
 // This must come before the CSP is set or it will be blocked.
 const metrics = requestFlowMetrics();
 
diff --git a/browser/components/nsBrowserContentHandler.js b/browser/components/nsBrowserContentHandler.js
index 6bc7f651fdd1..ecb08a61cd2f 100644
--- a/browser/components/nsBrowserContentHandler.js
+++ b/browser/components/nsBrowserContentHandler.js
@@ -15,6 +15,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   SessionStartup: "resource:///modules/sessionstore/SessionStartup.jsm",
   ShellService: "resource:///modules/ShellService.jsm",
   UpdatePing: "resource://gre/modules/UpdatePing.jsm",
+  RemotePages: "resource://gre/modules/remotepagemanager/RemotePageManagerParent.jsm",
 });
 XPCOMUtils.defineLazyServiceGetter(this, "WindowsUIUtils",
   "@mozilla.org/windows-ui-utils;1", "nsIWindowsUIUtils");
@@ -23,6 +24,8 @@ XPCOMUtils.defineLazyGetter(this, "gSystemPrincipal",
   () => Services.scriptSecurityManager.getSystemPrincipal());
 XPCOMUtils.defineLazyGlobalGetters(this, [URL]);
 
+const NEWINSTALL_PAGE = "about:newinstall";
+
 function shouldLoadURI(aURI) {
   if (aURI && !aURI.schemeIs("chrome"))
     return true;
@@ -60,12 +63,14 @@ function resolveURIInternal(aCmdLine, aArgument) {
   return uri;
 }
 
+let gRemoteInstallPage = null;
+
 function getNewInstallPage() {
-  let url = new URL("about:newinstall");
-  let endpoint = Services.prefs.getCharPref("browser.dedicatedprofile.welcome.accounts.endpoint");
-  url.searchParams.set("endpoint", endpoint);
-  url.searchParams.set("channel", AppConstants.MOZ_UPDATE_CHANNEL);
-  return url.toString();
+  if (!gRemoteInstallPage) {
+    gRemoteInstallPage = new RemotePages(NEWINSTALL_PAGE);
+  }
+
+  return NEWINSTALL_PAGE;
 }
 
 var gFirstWindow = false;
diff --git a/toolkit/components/remotepagemanager/MessagePort.jsm b/toolkit/components/remotepagemanager/MessagePort.jsm
index ba2f7ee4d839..da72b1549856 100644
--- a/toolkit/components/remotepagemanager/MessagePort.jsm
+++ b/toolkit/components/remotepagemanager/MessagePort.jsm
@@ -13,6 +13,8 @@ ChromeUtils.defineModuleGetter(this, "PrivateBrowsingUtils",
   "resource://gre/modules/PrivateBrowsingUtils.jsm");
 ChromeUtils.defineModuleGetter(this, "PromiseUtils",
   "resource://gre/modules/PromiseUtils.jsm");
+ChromeUtils.defineModuleGetter(this, "UpdateUtils",
+  "resource://gre/modules/UpdateUtils.jsm");
 
 /*
  * Used for all kinds of permissions checks which requires explicit
@@ -33,6 +35,10 @@ let RPMAccessManager = {
                            "app.support.baseURL"],
       "isWindowPrivate": ["yes"],
     },
+    "about:newinstall": {
+      "getUpdateChannel": ["yes"],
+      "getFxAccountsEndpoint": ["yes"],
+    },
   },
 
   checkAllowAccess(aPrincipal, aFeature, aValue) {
@@ -163,7 +169,7 @@ class MessagePort {
   // once the other process has responded to the request or some error occurs.
   sendRequest(name, data = null) {
     if (this.destroyed) {
-      return Promise.reject(new Error("Message port has been destroyed"));
+      return this.window.Promise.reject(new Error("Message port has been destroyed"));
     }
 
     let deferred = PromiseUtils.defer();
@@ -176,7 +182,7 @@ class MessagePort {
       data,
     });
 
-    return deferred.promise;
+    return this.wrapPromise(deferred.promise);
   }
 
   // Handles an IPC message to perform a request of some kind.
@@ -291,6 +297,10 @@ class MessagePort {
     this.requests = [];
   }
 
+  wrapPromise(promise) {
+    return new this.window.Promise((resolve, reject) => promise.then(resolve, reject));
+  }
+
   getBoolPref(aPref) {
     let principal = this.window.document.nodePrincipal;
     if (!RPMAccessManager.checkAllowAccess(principal, "getBoolPref", aPref)) {
@@ -300,11 +310,7 @@ class MessagePort {
   }
 
   setBoolPref(aPref, aVal) {
-    return new this.window.Promise(function(resolve) {
-      AsyncPrefs.set(aPref, aVal).then(function() {
-        resolve();
-      });
-    });
+    return this.wrapPromise(AsyncPrefs.set(aPref, aVal));
   }
 
   getFormatURLPref(aFormatURL) {
@@ -322,4 +328,21 @@ class MessagePort {
     }
     return PrivateBrowsingUtils.isContentWindowPrivate(this.window);
   }
+
+  getUpdateChannel() {
+    let principal = this.window.document.nodePrincipal;
+    if (!RPMAccessManager.checkAllowAccess(principal, "getUpdateChannel", "yes")) {
+      throw new Error("RPMAccessManager does not allow access to getUpdateChannel");
+    }
+    return UpdateUtils.UpdateChannel;
+  }
+
+  getFxAccountsEndpoint(aEntrypoint) {
+    let principal = this.window.document.nodePrincipal;
+    if (!RPMAccessManager.checkAllowAccess(principal, "getFxAccountsEndpoint", "yes")) {
+      throw new Error("RPMAccessManager does not allow access to getFxAccountsEndpoint");
+    }
+
+    return this.sendRequest("FxAccountsEndpoint", aEntrypoint);
+  }
 }
diff --git a/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm b/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm
index 0b359456ba3a..f6abd1714e5d 100644
--- a/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm
+++ b/toolkit/components/remotepagemanager/RemotePageManagerChild.jsm
@@ -41,6 +41,12 @@ class ChildMessagePort extends MessagePort {
     Cu.exportFunction(this.isWindowPrivate.bind(this), window, {
       defineAs: "RPMIsWindowPrivate",
     });
+    Cu.exportFunction(this.getUpdateChannel.bind(this), window, {
+      defineAs: "RPMGetUpdateChannel",
+    });
+    Cu.exportFunction(this.getFxAccountsEndpoint.bind(this), window, {
+      defineAs: "RPMGetFxAccountsEndpoint",
+    });
 
     // Send a message for load events
     let loadListener = () => {
diff --git a/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm b/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm
index f42e5ffbf589..f18a31a2d296 100644
--- a/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm
+++ b/toolkit/components/remotepagemanager/RemotePageManagerParent.jsm
@@ -21,6 +21,8 @@ var EXPORTED_SYMBOLS = ["RemotePages", "RemotePageManager"];
 
 const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
 const {MessageListener, MessagePort} = ChromeUtils.import("resource://gre/modules/remotepagemanager/MessagePort.jsm");
+ChromeUtils.defineModuleGetter(this, "FxAccounts",
+  "resource://gre/modules/FxAccounts.jsm");
 
 /**
  * Creates a RemotePages object which listens for new remote pages of some
@@ -236,6 +238,10 @@ class ChromeMessagePort extends MessagePort {
 
   // Called when the content process is requesting some data.
   async handleRequest(name, data) {
+    if (name == "FxAccountsEndpoint") {
+      return FxAccounts.config.promiseEmailFirstURI(data);
+    }
+
     throw new Error(`Unknown request ${name}.`);
   }