diff --git a/Podfile b/Podfile
index ffd1c3806..2616f47ba 100644
--- a/Podfile
+++ b/Podfile
@@ -5,8 +5,8 @@ target 'Signal' do
     pod 'SocketRocket',               :git => 'https://github.com/facebook/SocketRocket.git'
     pod 'AxolotlKit',                 git: 'https://github.com/WhisperSystems/SignalProtocolKit.git'
     #pod 'AxolotlKit',                 path: '../SignalProtocolKit'
-    pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git'
-    #pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git', :branch => 'charlesmchen/rateLimitingErrorMessage'
+    #pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git'
+    pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git', :branch => 'charlesmchen/markUnsentMessages'
     #pod 'SignalServiceKit',           path: '../SignalServiceKit'
     pod 'OpenSSL'
     pod 'PastelogKit',                '~> 1.3'
diff --git a/Podfile.lock b/Podfile.lock
index 27b757ebc..9e9994431 100644
--- a/Podfile.lock
+++ b/Podfile.lock
@@ -123,7 +123,7 @@ DEPENDENCIES:
   - PastelogKit (~> 1.3)
   - PureLayout
   - SCWaveformView (~> 1.0)
-  - SignalServiceKit (from `https://github.com/WhisperSystems/SignalServiceKit.git`)
+  - SignalServiceKit (from `https://github.com/WhisperSystems/SignalServiceKit.git`, branch `charlesmchen/markUnsentMessages`)
   - SocketRocket (from `https://github.com/facebook/SocketRocket.git`)
   - ZXingObjC
 
@@ -131,6 +131,7 @@ EXTERNAL SOURCES:
   AxolotlKit:
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
+    :branch: charlesmchen/markUnsentMessages
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :git: https://github.com/facebook/SocketRocket.git
@@ -140,7 +141,7 @@ CHECKOUT OPTIONS:
     :commit: 945c04f9e70f7119d2ada4edb938849f3b7febab
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :commit: 12027152f4bffd650badad73203bff788684d76d
+    :commit: c6fdcbb4986a04b184ae6591af44f1e162c9e29f
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :commit: 41b57bb2fc292a814f758441a05243eb38457027
@@ -172,6 +173,6 @@ SPEC CHECKSUMS:
   YapDatabase: b1e43555a34a5298e23a045be96817a5ef0da58f
   ZXingObjC: bf15b3814f7a105b6d99f47da2333c93a063650a
 
-PODFILE CHECKSUM: 23ca4df281ad1e794af6967db2047f43df88e96a
+PODFILE CHECKSUM: ab71a7c277b83315d9ca0ca86b9e2a2dc92af86a
 
 COCOAPODS: 1.1.1
diff --git a/Signal/src/AppDelegate.m b/Signal/src/AppDelegate.m
index 97933aaf0..cffeedd7a 100644
--- a/Signal/src/AppDelegate.m
+++ b/Signal/src/AppDelegate.m
@@ -24,6 +24,7 @@
 #import <PastelogKit/Pastelog.h>
 #import <PromiseKit/AnyPromise.h>
 #import <SignalServiceKit/OWSDisappearingMessagesJob.h>
+#import <SignalServiceKit/OWSFailedMessagesJob.h>
 #import <SignalServiceKit/OWSIncomingMessageReadObserver.h>
 #import <SignalServiceKit/OWSMessageSender.h>
 #import <SignalServiceKit/TSAccountManager.h>
@@ -168,6 +169,11 @@ static NSString *const kURLHostVerifyPrefix             = @"verify";
 
         // Clean up any messages that expired since last launch.
         [[[OWSDisappearingMessagesJob alloc] initWithStorageManager:[TSStorageManager sharedManager]] run];
+
+        // Mark all "attempting out" messages as "unsent", i.e. any messages that were not successfully
+        // sent before the app exited should be marked as failures.
+        [[[OWSFailedMessagesJob alloc] initWithStorageManager:[TSStorageManager sharedManager]] run];
+
         [AppStoreRating setupRatingLibrary];
     }];