diff --git a/browser/base/content/browser-sync.js b/browser/base/content/browser-sync.js
index 686c0c9b5ed2..82b0566e9329 100644
--- a/browser/base/content/browser-sync.js
+++ b/browser/base/content/browser-sync.js
@@ -645,7 +645,7 @@ var gSync = {
         // We are pretty confident that push helps us pick up all FxA commands,
         // but some users might have issues with push, so let's unblock them
         // by fetching the missed FxA commands on manual sync.
-        fxAccounts.commands.fetchMissedRemoteCommands().catch(e => {
+        fxAccounts.commands.pollDeviceCommands().catch(e => {
           console.error("Fetching missed remote commands failed.", e);
         });
         Weave.Service.sync();
diff --git a/browser/components/BrowserGlue.jsm b/browser/components/BrowserGlue.jsm
index 00723363512f..8017faf81902 100644
--- a/browser/components/BrowserGlue.jsm
+++ b/browser/components/BrowserGlue.jsm
@@ -2860,8 +2860,8 @@ BrowserGlue.prototype = {
       const firstTab = await openTab(URIs[0]);
       await Promise.all(URIs.slice(1).map(URI => openTab(URI)));
 
+      const deviceName = URIs[0].sender && URIs[0].sender.name;
       let title, body;
-      const deviceName = URIs[0].sender.name;
       const bundle = Services.strings.createBundle("chrome://browser/locale/accounts.properties");
       if (URIs.length == 1) {
         // Due to bug 1305895, tabs from iOS may not have device information, so
@@ -2885,13 +2885,15 @@ BrowserGlue.prototype = {
         }
       } else {
         title = bundle.GetStringFromName("multipleTabsArrivingNotification.title");
-        const allSameDevice = URIs.every(URI => URI.sender.id == URIs[0].sender.id);
-        const unknownDevice = allSameDevice && !deviceName;
+        const allKnownSender = URIs.every(URI => URI.sender != null);
+        const allSameDevice = allKnownSender && URIs.every(URI => URI.sender.id == URIs[0].sender.id);
         let tabArrivingBody;
-        if (unknownDevice) {
-          tabArrivingBody = "unnamedTabsArrivingNotificationNoDevice.body";
-        } else if (allSameDevice) {
-          tabArrivingBody = "unnamedTabsArrivingNotification2.body";
+        if (allSameDevice) {
+          if (deviceName) {
+            tabArrivingBody = "unnamedTabsArrivingNotification2.body";
+          } else {
+            tabArrivingBody = "unnamedTabsArrivingNotificationNoDevice.body";
+          }
         } else {
           tabArrivingBody = "unnamedTabsArrivingNotificationMultiple2.body";
         }
diff --git a/services/fxaccounts/FxAccountsCommands.js b/services/fxaccounts/FxAccountsCommands.js
index 05fff646a547..263aec8fd2b8 100644
--- a/services/fxaccounts/FxAccountsCommands.js
+++ b/services/fxaccounts/FxAccountsCommands.js
@@ -38,62 +38,52 @@ class FxAccountsCommands {
     log.info(`Payload sent to device ${device.id}.`);
   }
 
-  async consumeRemoteCommand(index) {
+  /**
+   * Poll and handle device commands for the current device.
+   * This method can be called either in response to a Push message,
+   * or by itself as a "commands recovery" mechanism.
+   *
+   * @param {Number} receivedIndex "Command received" push messages include
+   * the index of the command that triggered the message. We use it as a
+   * hint when we have no "last command index" stored.
+   */
+  async pollDeviceCommands(receivedIndex = 0) {
+    // Whether the call to `pollDeviceCommands` was initiated by a Push message from the FxA
+    // servers in response to a message being received or simply scheduled in order
+    // to fetch missed messages.
+    const scheduledFetch = receivedIndex == 0;
     if (!Services.prefs.getBoolPref("identity.fxaccounts.commands.enabled", true)) {
       return false;
     }
-    log.info(`Consuming command with index ${index}.`);
-    const {messages} = await this._fetchRemoteCommands(index, 1);
-    if (messages.length != 1) {
-      log.warn(`Should have retrieved 1 and only 1 message, got ${messages.length}.`);
-    }
-    return this._fxAccounts._withCurrentAccountState(async (getUserData, updateUserData) => {
-      const {device} = await getUserData(["device"]);
-      if (!device) {
-        throw new Error("No device registration.");
-      }
-      const handledCommands = (device.handledCommands || []).concat(messages.map(m => m.index));
-      await updateUserData({
-        device: {...device, handledCommands},
-      });
-      await this._handleCommands(messages);
-
-      // Once the handledCommands array length passes a threshold, check the
-      // potentially missed remote commands in order to clear it.
-      if (handledCommands.length > 20) {
-        await this.fetchMissedRemoteCommands();
-      }
-    });
-  }
-
-  async fetchMissedRemoteCommands() {
-    if (!Services.prefs.getBoolPref("identity.fxaccounts.commands.enabled", true)) {
-      return false;
-    }
-    log.info(`Consuming missed commands.`);
+    log.info(`Polling device commands.`);
     await this._fxAccounts._withCurrentAccountState(async (getUserData, updateUserData) => {
       const {device} = await getUserData(["device"]);
       if (!device) {
         throw new Error("No device registration.");
       }
-      const lastCommandIndex = device.lastCommandIndex || 0;
-      const handledCommands = device.handledCommands || [];
-      handledCommands.push(lastCommandIndex); // Because the server also returns this command.
-      const {index, messages} = await this._fetchRemoteCommands(lastCommandIndex);
-      const missedMessages = messages.filter(m => !handledCommands.includes(m.index));
-      await updateUserData({
-        device: {...device, lastCommandIndex: index, handledCommands: []},
-      });
-      if (missedMessages.length) {
-        log.info(`Handling ${missedMessages.length} missed messages`);
-        Services.telemetry.scalarAdd("identity.fxaccounts.missed_commands_fetched", missedMessages.length);
-        await this._handleCommands(missedMessages);
+      // We increment lastCommandIndex by 1 because the server response includes the current index.
+      // If we don't have a `lastCommandIndex` stored, we fall back on the index from the push message we just got.
+      const lastCommandIndex = (device.lastCommandIndex + 1) || receivedIndex;
+      // We have already received this message before.
+      if (receivedIndex > 0 && receivedIndex < lastCommandIndex) {
+        return;
+      }
+      const {index, messages} = await this._fetchDeviceCommands(lastCommandIndex);
+      if (messages.length) {
+        await updateUserData({
+          device: {...device, lastCommandIndex: index},
+        });
+        log.info(`Handling ${messages.length} messages`);
+        if (scheduledFetch) {
+          Services.telemetry.scalarAdd("identity.fxaccounts.missed_commands_fetched", messages.length);
+        }
+        await this._handleCommands(messages);
       }
     });
     return true;
   }
 
-  async _fetchRemoteCommands(index, limit = null) {
+  async _fetchDeviceCommands(index, limit = null) {
     const userData = await this._fxAccounts.getSignedInUser();
     if (!userData) {
       throw new Error("No user.");
@@ -112,15 +102,20 @@ class FxAccountsCommands {
 
   async _handleCommands(messages) {
     const fxaDevices = await this._fxAccounts.getDeviceList();
+    // We debounce multiple incoming tabs so we show a single notification.
+    const tabsReceived = [];
     for (const {data} of messages) {
-      let {command, payload, sender} = data;
-      if (sender) {
-        sender = fxaDevices.find(d => d.id == sender);
+      const {command, payload, sender: senderId} = data;
+      const sender = senderId ? fxaDevices.find(d => d.id == senderId) : null;
+      if (!sender) {
+        log.warn("Incoming command is from an unknown device (maybe disconnected?)");
       }
       switch (command) {
         case COMMAND_SENDTAB:
           try {
-            await this.sendTab.handle(sender, payload);
+            const {title, uri} = await this.sendTab.handle(payload);
+            log.info(`Tab received with FxA commands: ${title} from ${sender ? sender.name : "Unknown device"}.`);
+            tabsReceived.push({title, uri, sender});
           } catch (e) {
             log.error(`Error while handling incoming Send Tab payload.`, e);
           }
@@ -129,6 +124,9 @@ class FxAccountsCommands {
           log.info(`Unknown command: ${command}.`);
       }
     }
+    if (tabsReceived.length) {
+      Observers.notify("fxaccounts:commands:open-uri", tabsReceived);
+    }
   }
 }
 
@@ -184,22 +182,17 @@ class SendTab {
   }
 
   // Handle incoming send tab payload, called by FxAccountsCommands.
-  async handle(sender, {encrypted}) {
-    if (!sender) {
-      log.warn("Incoming tab is from an unknown device (maybe disconnected?)");
-    }
+  async handle({encrypted}) {
     const bytes = await this._decrypt(encrypted);
     const decoder = new TextDecoder("utf8");
     const data = JSON.parse(decoder.decode(bytes));
     const current = data.hasOwnProperty("current") ? data.current :
                                                      data.entries.length - 1;
-    const tabSender = {
-      id: sender ? sender.id : "",
-      name: sender ? sender.name : "",
-    };
     const {title, url: uri} = data.entries[current];
-    log.info(`Tab received with FxA commands: ${title} from ${tabSender.name}.`);
-    Observers.notify("fxaccounts:commands:open-uri", [{uri, title, sender: tabSender}]);
+    return {
+      title,
+      uri,
+    };
   }
 
   async _encrypt(bytes, device) {
diff --git a/services/fxaccounts/FxAccountsPush.jsm b/services/fxaccounts/FxAccountsPush.jsm
index 3a4e3e0b5e64..456a6f7c944a 100644
--- a/services/fxaccounts/FxAccountsPush.jsm
+++ b/services/fxaccounts/FxAccountsPush.jsm
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+const {Async} = ChromeUtils.import("resource://services-common/async.js");
 const {FXA_PUSH_SCOPE_ACCOUNT_UPDATE, ONLOGOUT_NOTIFICATION, ON_ACCOUNT_DESTROYED_NOTIFICATION, ON_ACCOUNT_STATE_CHANGE_NOTIFICATION, ON_COLLECTION_CHANGED_NOTIFICATION, ON_COMMAND_RECEIVED_NOTIFICATION, ON_DEVICE_CONNECTED_NOTIFICATION, ON_DEVICE_DISCONNECTED_NOTIFICATION, ON_PASSWORD_CHANGED_NOTIFICATION, ON_PASSWORD_RESET_NOTIFICATION, ON_PROFILE_CHANGE_NOTIFICATION, ON_PROFILE_UPDATED_NOTIFICATION, ON_VERIFY_LOGIN_NOTIFICATION, log} = ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js");
 
 /**
@@ -71,10 +72,17 @@ FxAccountsPushService.prototype = {
         "resource://gre/modules/FxAccounts.jsm");
     }
 
-    // listen to new push messages, push changes and logout events
-    Services.obs.addObserver(this, this.pushService.pushTopic);
-    Services.obs.addObserver(this, this.pushService.subscriptionChangeTopic);
-    Services.obs.addObserver(this, ONLOGOUT_NOTIFICATION);
+    this.asyncObserver = Async.asyncObserver(this, this.log);
+    // We use an async observer because a device waking up can
+    // observe multiple "Send Tab received" push notifications at the same time.
+    // The way these notifications are handled is as follows:
+    // Read index from storage, make network request, update the index.
+    // You can imagine what happens when multiple calls race: we load
+    // the same index multiple times and receive the same exact tabs, multiple times.
+    // The async observer will ensure we make these network requests serially.
+    Services.obs.addObserver(this.asyncObserver, this.pushService.pushTopic);
+    Services.obs.addObserver(this.asyncObserver, this.pushService.subscriptionChangeTopic);
+    Services.obs.addObserver(this.asyncObserver, ONLOGOUT_NOTIFICATION);
 
     this.log.debug("FxAccountsPush initialized");
     return true;
@@ -103,51 +111,50 @@ FxAccountsPushService.prototype = {
     });
   },
   /**
-   * Standard observer interface to listen to push messages, changes and logout.
+   * Async observer interface to listen to push messages, changes and logout.
    *
    * @param subject
    * @param topic
    * @param data
    * @returns {Promise}
    */
-  _observe(subject, topic, data) {
-    this.log.trace(`observed topic=${topic}, data=${data}, subject=${subject}`);
-    switch (topic) {
-      case this.pushService.pushTopic:
-        if (data === FXA_PUSH_SCOPE_ACCOUNT_UPDATE) {
-          let message = subject.QueryInterface(Ci.nsIPushMessage);
-          this._onPushMessage(message);
-        }
-        break;
-      case this.pushService.subscriptionChangeTopic:
-        if (data === FXA_PUSH_SCOPE_ACCOUNT_UPDATE) {
-          this._onPushSubscriptionChange();
-        }
-        break;
-      case ONLOGOUT_NOTIFICATION:
-        // user signed out, we need to stop polling the Push Server
-        this.unsubscribe().catch(err => {
-          this.log.error("Error during unsubscribe", err);
-        });
-      default:
-        break;
+  async observe(subject, topic, data) {
+    try {
+      this.log.trace(`observed topic=${topic}, data=${data}, subject=${subject}`);
+      switch (topic) {
+        case this.pushService.pushTopic:
+          if (data === FXA_PUSH_SCOPE_ACCOUNT_UPDATE) {
+            let message = subject.QueryInterface(Ci.nsIPushMessage);
+            await this._onPushMessage(message);
+          }
+          break;
+        case this.pushService.subscriptionChangeTopic:
+          if (data === FXA_PUSH_SCOPE_ACCOUNT_UPDATE) {
+            await this._onPushSubscriptionChange();
+          }
+          break;
+        case ONLOGOUT_NOTIFICATION:
+          // user signed out, we need to stop polling the Push Server
+          try {
+            await this.unsubscribe();
+          } catch (err) {
+            this.log.error("Error during unsubscribe", err);
+          }
+        default:
+          break;
+      }
+    } catch (err) {
+      this.log.error(err);
     }
   },
-  /**
-   * Wrapper around _observe that catches errors
-   */
-  observe(subject, topic, data) {
-    Promise.resolve()
-      .then(() => this._observe(subject, topic, data))
-      .catch(err => this.log.error(err));
-  },
+
   /**
    * Fired when the Push server sends a notification.
    *
    * @private
    * @returns {Promise}
    */
-  _onPushMessage(message) {
+  async _onPushMessage(message) {
     this.log.trace("FxAccountsPushService _onPushMessage");
     if (!message.data) {
       // Use the empty signal to check the verification state of the account right away
@@ -159,7 +166,7 @@ FxAccountsPushService.prototype = {
     this.log.debug(`push command: ${payload.command}`);
     switch (payload.command) {
       case ON_COMMAND_RECEIVED_NOTIFICATION:
-        this.fxAccounts.commands.consumeRemoteCommand(payload.data.index);
+        await this.fxAccounts.commands.pollDeviceCommands(payload.data.index);
         break;
       case ON_DEVICE_CONNECTED_NOTIFICATION:
         Services.obs.notifyObservers(null, ON_DEVICE_CONNECTED_NOTIFICATION, payload.data.deviceName);
diff --git a/services/fxaccounts/tests/xpcshell/test_commands.js b/services/fxaccounts/tests/xpcshell/test_commands.js
index ba8b000a1c2f..3426d48b269c 100644
--- a/services/fxaccounts/tests/xpcshell/test_commands.js
+++ b/services/fxaccounts/tests/xpcshell/test_commands.js
@@ -50,15 +50,30 @@ add_task(async function test_sendtab_send() {
   Assert.ok(commands.invoke.calledTwice);
 });
 
-add_task(async function test_commands_fetchMissedRemoteCommands() {
+add_task(async function test_commands_pollDeviceCommands_push() {
+  // Server state.
+  const remoteMessages = [
+    {
+      index: 11,
+      data: {},
+    },
+    {
+      index: 12,
+      data: {},
+    },
+  ];
+  const remoteIndex = 12;
+
+  // Local state.
+  const pushIndexReceived = 11;
   const accountState = {
     data: {
       device: {
-        handledCommands: [8, 9, 10, 11],
-        lastCommandIndex: 11,
+        lastCommandIndex: 10,
       },
     },
   };
+
   const fxAccounts = {
     async _withCurrentAccountState(cb) {
       const get = () => accountState.data;
@@ -67,26 +82,168 @@ add_task(async function test_commands_fetchMissedRemoteCommands() {
     },
   };
   const commands = new FxAccountsCommands(fxAccounts);
-  commands._fetchRemoteCommands = () => {
-    return {
-      index: 12,
-      messages: [
-        {
-          index: 11,
-          data: {},
-        },
-        {
-          index: 12,
-          data: {},
-        },
-      ],
-    };
-  };
-  commands._handleCommands = sinon.spy();
-  await commands.fetchMissedRemoteCommands();
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").once().withArgs(11).returns({
+    index: remoteIndex,
+    messages: remoteMessages,
+  });
+  mockCommands.expects("_handleCommands").once().withArgs(remoteMessages);
+  await commands.pollDeviceCommands(pushIndexReceived);
 
-  Assert.equal(accountState.data.device.handledCommands.length, 0);
+  mockCommands.verify();
+  Assert.equal(accountState.data.device.lastCommandIndex, 12);
+});
+
+add_task(async function test_commands_pollDeviceCommands_push_already_fetched() {
+  // Local state.
+  const pushIndexReceived = 12;
+  const accountState = {
+    data: {
+      device: {
+        lastCommandIndex: 12,
+      },
+    },
+  };
+
+  const fxAccounts = {
+    async _withCurrentAccountState(cb) {
+      const get = () => accountState.data;
+      const set = (val) => { accountState.data = val; };
+      await cb(get, set);
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").never();
+  mockCommands.expects("_handleCommands").never();
+  await commands.pollDeviceCommands(pushIndexReceived);
+
+  mockCommands.verify();
+  Assert.equal(accountState.data.device.lastCommandIndex, 12);
+});
+
+add_task(async function test_commands_pollDeviceCommands_push_local_state_empty() {
+  // Server state.
+  const remoteMessages = [
+    {
+      index: 11,
+      data: {},
+    },
+    {
+      index: 12,
+      data: {},
+    },
+  ];
+  const remoteIndex = 12;
+
+  // Local state.
+  const pushIndexReceived = 11;
+  const accountState = {
+    data: {
+      device: {},
+    },
+  };
+
+  const fxAccounts = {
+    async _withCurrentAccountState(cb) {
+      const get = () => accountState.data;
+      const set = (val) => { accountState.data = val; };
+      await cb(get, set);
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").once().withArgs(11).returns({
+    index: remoteIndex,
+    messages: remoteMessages,
+  });
+  mockCommands.expects("_handleCommands").once().withArgs(remoteMessages);
+  await commands.pollDeviceCommands(pushIndexReceived);
+
+  mockCommands.verify();
+  Assert.equal(accountState.data.device.lastCommandIndex, 12);
+});
+
+add_task(async function test_commands_pollDeviceCommands_scheduled_local() {
+  // Server state.
+  const remoteMessages = [
+    {
+      index: 11,
+      data: {},
+    },
+    {
+      index: 12,
+      data: {},
+    },
+  ];
+  const remoteIndex = 12;
+
+  // Local state.
+  const accountState = {
+    data: {
+      device: {
+        lastCommandIndex: 10,
+      },
+    },
+  };
+
+  const fxAccounts = {
+    async _withCurrentAccountState(cb) {
+      const get = () => accountState.data;
+      const set = (val) => { accountState.data = val; };
+      await cb(get, set);
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").once().withArgs(11).returns({
+    index: remoteIndex,
+    messages: remoteMessages,
+  });
+  mockCommands.expects("_handleCommands").once().withArgs(remoteMessages);
+  await commands.pollDeviceCommands();
+
+  mockCommands.verify();
+  Assert.equal(accountState.data.device.lastCommandIndex, 12);
+});
+
+add_task(async function test_commands_pollDeviceCommands_scheduled_local_state_empty() {
+  // Server state.
+  const remoteMessages = [
+    {
+      index: 11,
+      data: {},
+    },
+    {
+      index: 12,
+      data: {},
+    },
+  ];
+  const remoteIndex = 12;
+
+  // Local state.
+  const accountState = {
+    data: {
+      device: {},
+    },
+  };
+
+  const fxAccounts = {
+    async _withCurrentAccountState(cb) {
+      const get = () => accountState.data;
+      const set = (val) => { accountState.data = val; };
+      await cb(get, set);
+    },
+  };
+  const commands = new FxAccountsCommands(fxAccounts);
+  const mockCommands = sinon.mock(commands);
+  mockCommands.expects("_fetchDeviceCommands").once().withArgs(0).returns({
+    index: remoteIndex,
+    messages: remoteMessages,
+  });
+  mockCommands.expects("_handleCommands").once().withArgs(remoteMessages);
+  await commands.pollDeviceCommands();
+
+  mockCommands.verify();
   Assert.equal(accountState.data.device.lastCommandIndex, 12);
-  const callArgs = commands._handleCommands.args[0][0];
-  Assert.equal(callArgs[0].index, 12);
 });
diff --git a/services/fxaccounts/tests/xpcshell/test_push_service.js b/services/fxaccounts/tests/xpcshell/test_push_service.js
index 046d0d5bc89b..e04b6023f61e 100644
--- a/services/fxaccounts/tests/xpcshell/test_push_service.js
+++ b/services/fxaccounts/tests/xpcshell/test_push_service.js
@@ -426,7 +426,7 @@ add_task(async function commandReceived() {
   let fxAccountsMock = {};
   const promiseConsumeRemoteMessagesCalled = new Promise(res => {
     fxAccountsMock.commands = {
-      consumeRemoteCommand() {
+      pollDeviceCommands() {
         res();
       },
     };
diff --git a/services/sync/modules/policies.js b/services/sync/modules/policies.js
index 154b6bb03c60..79c6a6d95683 100644
--- a/services/sync/modules/policies.js
+++ b/services/sync/modules/policies.js
@@ -550,7 +550,7 @@ SyncScheduler.prototype = {
       // Only fetch missed messages in a "scheduled" sync so we don't race against
       // the Push service reconnecting on a network link change for example.
       if (why == "schedule" && now >= this.missedFxACommandsLastFetch + this.missedFxACommandsFetchInterval) {
-        fxAccounts.commands.fetchMissedRemoteCommands().then(() => {
+        fxAccounts.commands.pollDeviceCommands().then(() => {
           this.missedFxACommandsLastFetch = now;
         }).catch(e => {
           this._log.error("Fetching missed remote commands failed.", e);