--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -1277,17 +1277,16 @@ pref("browser.newtabpage.activity-stream
 // ASRouter provider configuration
 pref("browser.newtabpage.activity-stream.asrouter.providers.cfr", "{\"id\":\"cfr\",\"enabled\":true,\"type\":\"remote-settings\",\"bucket\":\"cfr\",\"frequency\":{\"custom\":[{\"period\":\"daily\",\"cap\":1}]},\"categories\":[\"cfrAddons\",\"cfrFeatures\"],\"updateCycleInMs\":3600000}");
 pref("browser.newtabpage.activity-stream.asrouter.providers.whats-new-panel", "{\"id\":\"whats-new-panel\",\"enabled\":true,\"type\":\"remote-settings\",\"bucket\":\"whats-new-panel\",\"updateCycleInMs\":3600000}");
 pref("browser.newtabpage.activity-stream.asrouter.providers.message-groups", "{\"id\":\"message-groups\",\"enabled\":true,\"type\":\"remote-settings\",\"bucket\":\"message-groups\",\"updateCycleInMs\":3600000}");
 // This url, if changed, MUST continue to point to an https url. Pulling arbitrary content to inject into
 // this page over http opens us up to a man-in-the-middle attack that we'd rather not face. If you are a downstream
 // repackager of this code using an alternate snippet url, please keep your users safe
 pref("browser.newtabpage.activity-stream.asrouter.providers.snippets", "{\"id\":\"snippets\",\"enabled\":true,\"type\":\"remote\",\"url\":\"https://snippets.cdn.mozilla.net/%STARTPAGE_VERSION%/%NAME%/%VERSION%/%APPBUILDID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/\",\"updateCycleInMs\":14400000}");
-pref("browser.newtabpage.activity-stream.asrouter.providers.snippets-preview", "{\"id\":\"snippets-preview\",\"enabled\":true,\"type\":\"remote\",\"url\":\"\",\"updateCycleInMs\":0}");
 #ifdef NIGHTLY_BUILD
   pref("browser.newtabpage.activity-stream.asrouter.useReleaseSnippets", true);
 #endif
 
 // The pref that controls if ASRouter uses the remote fluent files.
 // It's enabled by default, but could be disabled to force ASRouter to use the local files.
 pref("browser.newtabpage.activity-stream.asrouter.useRemoteL10n", true);
 

--- a/browser/components/newtab/lib/ASRouter.jsm
+++ b/browser/components/newtab/lib/ASRouter.jsm
@@ -63,22 +63,21 @@ const { AttributionCode } = ChromeUtils.
 const TRAILHEAD_CONFIG = {
   DID_SEE_ABOUT_WELCOME_PREF: "trailhead.firstrun.didSeeAboutWelcome",
   DYNAMIC_TRIPLET_BUNDLE_LENGTH: 3,
 };
 
 const INCOMING_MESSAGE_NAME = "ASRouter:child-to-parent";
 const OUTGOING_MESSAGE_NAME = "ASRouter:parent-to-child";
 const ONE_DAY_IN_MS = 24 * 60 * 60 * 1000;
-const PREVIEW_SNIPPETS_ID = "snippets-preview";
 // List of hosts for endpoints that serve router messages.
 // Key is allowed host, value is a name for the endpoint host.
 const DEFAULT_WHITELIST_HOSTS = {
   "activity-stream-icons.services.mozilla.com": "production",
-  "snippets-admin.mozilla.org": PREVIEW_SNIPPETS_ID,
+  "snippets-admin.mozilla.org": "preview",
 };
 const SNIPPETS_ENDPOINT_WHITELIST =
   "browser.newtab.activity-stream.asrouter.whitelistHosts";
 // Max possible impressions cap for any message
 const MAX_MESSAGE_LIFETIME_CAP = 100;
 
 const LOCAL_MESSAGE_PROVIDERS = {
   OnboardingMessageProvider,
@@ -599,17 +598,17 @@ class _ASRouter {
     }
   }
 
   // Fetch and decode the message provider pref JSON, and update the message providers
   _updateMessageProviders() {
     const previousProviders = this.state.providers;
     const providers = [
       // If we have added a `preview` provider, hold onto it
-      ...previousProviders.filter(p => p.id === PREVIEW_SNIPPETS_ID),
+      ...previousProviders.filter(p => p.id === "preview"),
       // The provider should be enabled and not have a user preference set to false
       ...ASRouterPreferences.providers.filter(
         p =>
           p.enabled &&
           (ASRouterPreferences.getUserPreference(p.id) !== false &&
             // Provider is enabled or if provider has multiple categories
             // check that at least one category is enabled
             (!p.categories ||
@@ -694,32 +693,32 @@ class _ASRouter {
   }
 
   /**
    * Check all provided groups are enabled
    * @param groups Set of groups to verify
    * @returns bool
    */
   hasGroupsEnabled(groups = []) {
-    if (groups.includes(PREVIEW_SNIPPETS_ID)) {
-      return true;
-    }
     return this.state.groups
       .filter(({ id }) => groups.includes(id))
       .every(({ enabled }) => enabled);
   }
 
   /**
    * Verify that the provider block the message through the `exclude` field
    * @param message Message to verify
    * @returns bool
    */
   isExcludedByProvider(message) {
     const provider = this.state.providers.find(p => p.id === message.provider);
-    if (provider && provider.exclude) {
+    if (!provider) {
+      return true;
+    }
+    if (provider.exclude) {
       return provider.exclude.includes(message.id);
     }
     return false;
   }
 
   /**
    * Fetch all message groups and update Router.state.groups
    * There are 3 types of groups:
@@ -845,17 +844,17 @@ class _ASRouter {
       }
       // We don't need these listeners, but they may have previously been
       // initialised, so uninitialise them
       for (const triggerID of unseenListeners) {
         ASRouterTriggerListeners.get(triggerID).uninit();
       }
 
       // We don't want to cache preview endpoints, remove them after messages are fetched
-      await this.setState(this._disablePreviewEndpoint(newState));
+      await this.setState(this._removePreviewEndpoint(newState));
       await this.cleanupImpressions();
     }
   }
 
   async _maybeUpdateL10nAttachment() {
     const { localeInUse } = this.state.localeInUse;
     const newLocale = Services.locale.appLocaleAsBCP47;
     if (newLocale !== localeInUse) {
@@ -1753,17 +1752,17 @@ class _ASRouter {
     if (!additionalHosts.length) {
       return DEFAULT_WHITELIST_HOSTS;
     }
 
     // If there are additional hosts we want to whitelist, add them as
     // `preview` so that the updateCycle is 0
     return additionalHosts.reduce(
       (whitelist_hosts, host) => {
-        whitelist_hosts[host] = PREVIEW_SNIPPETS_ID;
+        whitelist_hosts[host] = "preview";
         Services.console.logStringMessage(`Adding ${host} to whitelist hosts.`);
         return whitelist_hosts;
       },
       { ...DEFAULT_WHITELIST_HOSTS }
     );
   }
 
   // To be passed to ASRouterTriggerListeners
@@ -1773,48 +1772,37 @@ class _ASRouter {
       return;
     }
     await this.onMessage({
       target,
       data: { type: "TRIGGER", data: { trigger } },
     });
   }
 
-  _disablePreviewEndpoint(state) {
-    const previewProvider = this.state.providers.find(
-      p => p.id === PREVIEW_SNIPPETS_ID
-    );
-    if (previewProvider && previewProvider.enabled) {
-      const providers = this.state.providers.filter(
-        p => p.id !== PREVIEW_SNIPPETS_ID
-      );
-      previewProvider.url = "";
-      previewProvider.enabled = false;
-      providers.push(previewProvider);
-      state.providers = providers;
-    }
-
+  _removePreviewEndpoint(state) {
+    state.providers = state.providers.filter(p => p.id !== "preview");
     return state;
   }
 
   async _addPreviewEndpoint(url, portID) {
-    const providers = [...this.state.providers].filter(
-      p => p.id !== PREVIEW_SNIPPETS_ID
-    );
-    const previewProvider = this.state.providers.find(
-      p => p.id === PREVIEW_SNIPPETS_ID
-    );
-    if (this._validPreviewEndpoint(url)) {
+    // When you view a preview snippet we want to hide all real content
+    const providers = [...this.state.providers];
+    if (
+      this._validPreviewEndpoint(url) &&
+      !providers.find(p => p.url === url)
+    ) {
       this.dispatchToAS(
-        // When you view a preview snippet we want to hide all real content
         ac.OnlyToOneContent({ type: at.SNIPPETS_PREVIEW_MODE }, portID)
       );
-      previewProvider.enabled = true;
-      previewProvider.url = url;
-      providers.push(previewProvider);
+      providers.push({
+        id: "preview",
+        type: "remote",
+        url,
+        updateCycleInMs: 0,
+      });
       await this.setState({ providers });
     }
   }
 
   // Windows specific calls to write attribution data
   // Used by `forceAttribution` to set required targeting attributes for
   // RTAMO messages. This should only be called from within about:newtab#asrouter
   /* istanbul ignore next */
@@ -2027,19 +2015,17 @@ class _ASRouter {
     if (endpoint) {
       await this._addPreviewEndpoint(endpoint.url, target.portID);
     }
 
     // Load all messages
     await this.loadMessagesFromAllProviders();
 
     if (endpoint) {
-      message = await this.handleMessageRequest({
-        provider: PREVIEW_SNIPPETS_ID,
-      });
+      message = await this.handleMessageRequest({ provider: "preview" });
 
       // We don't want to cache preview messages, remove them after we selected the message to show
       if (message) {
         await this.setState(state => ({
           messages: state.messages.filter(m => m.id !== message.id),
         }));
       }
     } else {
@@ -2177,17 +2163,22 @@ class _ASRouter {
           this._storage.set("messageBlockList", messageBlockList);
           return { messageBlockList };
         });
         break;
       case "OVERRIDE_MESSAGE":
         await this.setMessageById(action.data.id, target, true, action);
         break;
       case "ADMIN_CONNECT_STATE":
-        await this._updateAdminState(target);
+        if (action.data && action.data.endpoint) {
+          this._addPreviewEndpoint(action.data.endpoint.url, target.portID);
+          await this.loadMessagesFromAllProviders();
+        } else {
+          await this._updateAdminState(target);
+        }
         break;
       case "IMPRESSION":
         await this.addImpression(action.data);
         break;
       case "DOORHANGER_TELEMETRY":
       case "TOOLBAR_BADGE_TELEMETRY":
       case "TOOLBAR_PANEL_TELEMETRY":
         if (this.dispatchToAS) {

--- a/browser/components/newtab/test/browser/browser.ini
+++ b/browser/components/newtab/test/browser/browser.ini
@@ -1,14 +1,13 @@
 [DEFAULT]
 support-files =
   blue_page.html
   red_page.html
   head.js
-  snippet.json
 prefs =
   browser.newtabpage.activity-stream.debug=false
   browser.newtabpage.activity-stream.discoverystream.enabled=true
   browser.newtabpage.activity-stream.discoverystream.endpoints=data:
   browser.newtabpage.activity-stream.feeds.section.topstories=true
   browser.newtabpage.activity-stream.feeds.section.topstories.options={"provider_name":""}
 
 [browser_aboutwelcome.js]

--- a/browser/components/newtab/test/browser/browser_asrouter_snippets.js
+++ b/browser/components/newtab/test/browser/browser_asrouter_snippets.js
@@ -59,43 +59,8 @@ test_newtab({
     );
 
     ok(
       !content.document.querySelector(".below-search-snippet"),
       "Should not find any snippets below search"
     );
   },
 });
-
-add_task(async () => {
-  ASRouter._validPreviewEndpoint = () => true;
-  await BrowserTestUtils.withNewTab(
-    {
-      gBrowser,
-      url:
-        "about:newtab?endpoint=https://example.com/browser/browser/components/newtab/test/browser/snippet.json",
-    },
-    async browser => {
-      let text = await SpecialPowers.spawn(browser, [], async () => {
-        await ContentTaskUtils.waitForCondition(
-          () => content.document.querySelector(".activity-stream"),
-          `Should render Activity Stream`
-        );
-        await ContentTaskUtils.waitForCondition(
-          () =>
-            content.document.querySelector(
-              "#footer-asrouter-container .SimpleSnippet"
-            ),
-          "Should find the snippet inside the footer container"
-        );
-
-        return content.document.querySelector("#footer-asrouter-container")
-          .innerText;
-      });
-
-      Assert.equal(
-        text,
-        "On January 30th Nightly will introduce dedicated profiles, making it simpler to run different installations of Firefox side by side. Learn what this means for you.",
-        "Snippet content match"
-      );
-    }
-  );
-});

deleted file mode 100644
--- a/browser/components/newtab/test/browser/snippet.json
+++ /dev/null
@@ -1,25 +0,0 @@
-{
-  "messages": [
-    {
-      "weight": 50,
-      "id": "10533",
-      "template": "simple_snippet",
-      "template_version": "1.0.0",
-      "content": {
-        "icon": "",
-        "text": "On January 30th Nightly will introduce dedicated profiles, making it simpler to run different installations of Firefox side by side. <link0> Learn what this means for you</link0>.",
-        "tall": false,
-        "do_not_autoblock": false,
-        "links": {
-          "link0": {
-            "url": "https://support.mozilla.org/kb/dedicated-profiles-firefox-installation/?utm_source=desktop-snippet&utm_medium=snippet&utm_campaign=nightly_profile_management&utm_term=10533&utm_content=nightly"
-          }
-        }
-      },
-      "campaign": "nightly-profile-management",
-      "targeting": "true",
-      "provider_url": "https://snippets.cdn.mozilla.net/6/Firefox/66.0a1/20190122215349/Darwin_x86_64-gcc3/en-US/default/Darwin%2018.0.0/default/default/",
-      "provider": "snippets"
-    }
-  ]
-}

--- a/browser/components/newtab/test/unit/asrouter/ASRouter.test.js
+++ b/browser/components/newtab/test/unit/asrouter/ASRouter.test.js
@@ -45,17 +45,16 @@ const USE_REMOTE_L10N_PREF =
 function fakeAsyncMessage(action) {
   return { data: action, target: new FakeRemotePageManager() };
 }
 // Create a message that looks like a user action
 function fakeExecuteUserAction(action) {
   return fakeAsyncMessage({ data: action, type: "USER_ACTION" });
 }
 
-// eslint-disable-next-line max-statements
 describe("ASRouter", () => {
   let Router;
   let globals;
   let channel;
   let sandbox;
   let messageBlockList;
   let providerBlockList;
   let messageImpressions;
@@ -341,33 +340,29 @@ describe("ASRouter", () => {
         Router.state.messages,
         FAKE_LOCAL_MESSAGES.length + FAKE_REMOTE_MESSAGES.length
       );
     });
     it("should load additional whitelisted hosts", async () => {
       getStringPrefStub.returns('["whitelist.com"]');
       await createRouterAndInit();
 
-      assert.propertyVal(
-        Router.WHITELIST_HOSTS,
-        "whitelist.com",
-        "snippets-preview"
-      );
+      assert.propertyVal(Router.WHITELIST_HOSTS, "whitelist.com", "preview");
       // Should still include the defaults
       assert.lengthOf(Object.keys(Router.WHITELIST_HOSTS), 3);
     });
     it("should fallback to defaults if pref parsing fails", async () => {
       getStringPrefStub.returns("err");
       await createRouterAndInit();
 
       assert.lengthOf(Object.keys(Router.WHITELIST_HOSTS), 2);
       assert.propertyVal(
         Router.WHITELIST_HOSTS,
         "snippets-admin.mozilla.org",
-        "snippets-preview"
+        "preview"
       );
       assert.propertyVal(
         Router.WHITELIST_HOSTS,
         "activity-stream-icons.services.mozilla.com",
         "production"
       );
     });
     it("should set this.dispatchToAS to the third parameter passed to .init()", async () => {
@@ -1156,38 +1151,16 @@ describe("ASRouter", () => {
         messageBlockList: ["foocampaign"],
       }));
 
       const result = await Router.handleMessageRequest({
         provider: "snippets",
       });
       assert.isNull(result);
     });
-    it("should allow messages with undefined providers (like 'preview')", async () => {
-      sandbox.stub(Router, "loadMessagesFromAllProviders");
-      await Router.setState(() => ({
-        providers: [{ id: "snippets", exclude: ["foo"] }],
-      }));
-
-      await Router.setState(() => ({
-        messages: [
-          {
-            id: "foo",
-            provider: "snippets-preview",
-            groups: ["snippets-preview"],
-          },
-        ],
-        messageBlockList: ["foocampaign"],
-      }));
-
-      const result = await Router.handleMessageRequest({
-        provider: "snippets-preview",
-      });
-      assert.propertyVal(result, "provider", "snippets-preview");
-    });
     it("should not return a message if the frequency cap has been hit", async () => {
       sandbox.stub(Router, "isBelowFrequencyCaps").returns(false);
       await Router.setState(() => ({
         messages: [{ id: "foo", provider: "snippets" }],
       }));
       const result = await Router.handleMessageRequest({
         provider: "snippets",
       });
@@ -1658,39 +1631,38 @@ describe("ASRouter", () => {
         assert.calledWith(
           msg.target.sendAsyncMessage,
           PARENT_TO_CHILD_MESSAGE_NAME,
           { type: "CLEAR_ALL" }
         );
       });
     });
     describe("#_addPreviewEndpoint", () => {
-      beforeEach(async () => {
-        await Router.setState(state => {
-          const providers = [...state.providers];
-          const snippetsPreview = {
-            id: "snippets-preview",
-            enabled: false,
-            type: "remote",
-          };
-          providers.push(snippetsPreview);
-          return { providers };
-        });
-      });
       it("should make a request to the provided endpoint on NEWTAB_MESSAGE_REQUEST", async () => {
         const url = "https://snippets-admin.mozilla.org/foo";
         const msg = fakeAsyncMessage({
           type: "NEWTAB_MESSAGE_REQUEST",
           data: { endpoint: { url } },
         });
         await Router.onMessage(msg);
 
         assert.calledWith(global.fetch, url);
         assert.lengthOf(Router.state.providers.filter(p => p.url === url), 0);
       });
+      it("should make a request to the provided endpoint on ADMIN_CONNECT_STATE and remove the endpoint", async () => {
+        const url = "https://snippets-admin.mozilla.org/foo";
+        const msg = fakeAsyncMessage({
+          type: "ADMIN_CONNECT_STATE",
+          data: { endpoint: { url } },
+        });
+        await Router.onMessage(msg);
+
+        assert.calledWith(global.fetch, url);
+        assert.lengthOf(Router.state.providers.filter(p => p.url === url), 0);
+      });
       it("should dispatch SNIPPETS_PREVIEW_MODE when adding a preview endpoint", async () => {
         const url = "https://snippets-admin.mozilla.org/foo";
         const msg = fakeAsyncMessage({
           type: "NEWTAB_MESSAGE_REQUEST",
           data: { endpoint: { url } },
         });
         await Router.onMessage(msg);
 
@@ -2036,33 +2008,33 @@ describe("ASRouter", () => {
           Router.sendNewTabMessage,
           sinon.match.instanceOf(FakeRemotePageManager),
           data
         );
       });
       it("should return the preview message if that's available and remove it from Router.state", async () => {
         const expectedObj = {
           id: "foo",
-          groups: ["snippets-preview"],
-          provider: "snippets-preview",
+          groups: ["preview"],
+          provider: "preview",
         };
         Router.setState({
           messages: [expectedObj],
-          providers: [{ id: "snippets-preview" }],
+          providers: [{ id: "preview" }],
         });
 
         await Router.sendNewTabMessage(channel, { endpoint: "foo.com" });
 
         assert.calledWith(
           channel.sendAsyncMessage,
           PARENT_TO_CHILD_MESSAGE_NAME,
           { type: "SET_MESSAGE", data: expectedObj }
         );
         assert.isUndefined(
-          Router.state.messages.find(m => m.provider === "snippets-preview")
+          Router.state.messages.find(m => m.provider === "preview")
         );
       });
       it("should call _getBundledMessages if we request a message that needs to be bundled", async () => {
         sandbox.stub(Router, "_getBundledMessages").resolves();
         // forcefully pick a message which needs to be bundled (the second message in FAKE_LOCAL_MESSAGES)
         const [, testMessage] = Router.state.messages;
         const msg = fakeAsyncMessage({
           type: "OVERRIDE_MESSAGE",
@@ -3542,33 +3514,16 @@ describe("ASRouter", () => {
         messageImpressions = { foo: [0], bar: [] };
 
         await createRouterAndInit([
           { id: "onboarding", type: "local", messages, enabled: true },
         ]);
         assert.notCalled(Router._storage.set);
         assert.deepEqual(Router.state.messageImpressions, messageImpressions);
       });
-      it("should call setState before calling cleanupImpressions", async () => {
-        // The call order in `loadMessagesFromAllProviders` is important
-        const messages = [
-          { id: "foo", frequency: { lifetime: 10 } },
-          { id: "bar", frequency: { lifetime: 10 } },
-        ];
-        const setStateStub = sandbox.stub(Router, "setState");
-        const cleanupImpressionsStub = sandbox.stub(
-          Router,
-          "cleanupImpressions"
-        );
-        await createRouterAndInit([
-          { id: "onboarding", type: "local", messages, enabled: true },
-        ]);
-
-        cleanupImpressionsStub.calledImmediatelyAfter(setStateStub);
-      });
     });
   });
 
   describe("handle targeting errors", () => {
     beforeEach(() => {
       sandbox.stub(Router, "loadMessagesFromAllProviders");
     });
     it("should dispatch an event when a targeting expression throws an error", async () => {
@@ -4078,30 +4033,9 @@ describe("ASRouter", () => {
 
       assert.calledOnce(Router.setGroupState);
       assert.calledWithExactly(Router.setGroupState, {
         id: "unblock",
         value: true,
       });
     });
   });
-  describe("#loadMessagesForProvider", () => {
-    it("should fetch json from url", async () => {
-      let result = await MessageLoaderUtils.loadMessagesForProvider({
-        location: "http://fake.com/endpoint",
-        type: "json",
-      });
-
-      assert.property(result, "messages");
-      assert.lengthOf(result.messages, FAKE_REMOTE_MESSAGES.length);
-    });
-    it("should catch errors", async () => {
-      fetchStub.throws();
-      let result = await MessageLoaderUtils.loadMessagesForProvider({
-        location: "http://fake.com/endpoint",
-        type: "json",
-      });
-
-      assert.property(result, "messages");
-      assert.lengthOf(result.messages, 0);
-    });
-  });
 });

--- a/testing/profiles/common/user.js
+++ b/testing/profiles/common/user.js
@@ -4,17 +4,16 @@ user_pref("app.update.checkInstallTime",
 user_pref("app.update.disabledForTesting", true);
 user_pref("browser.chrome.guess_favicon", false);
 user_pref("browser.dom.window.dump.enabled", true);
 user_pref("devtools.console.stdout.chrome", true);
 // Use a python-eval-able empty JSON array even though asrouter expects plain object
 user_pref("browser.newtabpage.activity-stream.asrouter.providers.cfr", "[]");
 user_pref("browser.newtabpage.activity-stream.asrouter.providers.cfr-fxa", "[]");
 user_pref("browser.newtabpage.activity-stream.asrouter.providers.snippets", "[]");
-user_pref("browser.newtabpage.activity-stream.asrouter.providers.snippets-preview", "[]");
 user_pref("browser.newtabpage.activity-stream.feeds.section.topstories", false);
 user_pref("browser.newtabpage.activity-stream.feeds.snippets", false);
 user_pref("browser.newtabpage.activity-stream.tippyTop.service.endpoint", "");
 user_pref("browser.newtabpage.activity-stream.discoverystream.config", "[]");
 
 // For Activity Stream firstrun page, use an empty string to avoid fetching.
 user_pref("browser.newtabpage.activity-stream.fxaccounts.endpoint", "");
 // Background thumbnails in particular cause grief, and disabling thumbnails