diff --git a/src/Contacts/Threads/TSGroupThread.h b/src/Contacts/Threads/TSGroupThread.h
index a91e79676..56b6d5a83 100644
--- a/src/Contacts/Threads/TSGroupThread.h
+++ b/src/Contacts/Threads/TSGroupThread.h
@@ -12,6 +12,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 @property (nonatomic, strong) TSGroupModel *groupModel;
 
++ (instancetype)getOrCreateThreadWithGroupModel:(TSGroupModel *)groupModel;
 + (instancetype)getOrCreateThreadWithGroupModel:(TSGroupModel *)groupModel
                                     transaction:(YapDatabaseReadWriteTransaction *)transaction;
 
diff --git a/src/Contacts/Threads/TSGroupThread.m b/src/Contacts/Threads/TSGroupThread.m
index 3783fdaa5..327ce7f0f 100644
--- a/src/Contacts/Threads/TSGroupThread.m
+++ b/src/Contacts/Threads/TSGroupThread.m
@@ -5,6 +5,7 @@
 #import "NSData+Base64.h"
 #import "SignalRecipient.h"
 #import "TSAttachmentStream.h"
+#import <YapDatabase/YapDatabaseConnection.h>
 #import <YapDatabase/YapDatabaseTransaction.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -65,6 +66,15 @@ NS_ASSUME_NONNULL_BEGIN
     return thread;
 }
 
++ (instancetype)getOrCreateThreadWithGroupModel:(TSGroupModel *)groupModel
+{
+    __block TSGroupThread *thread;
+    [[self dbConnection] readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+        thread = [self getOrCreateThreadWithGroupModel:groupModel transaction:transaction];
+    }];
+    return thread;
+}
+
 + (NSString *)threadIdFromGroupId:(NSData *)groupId
 {
     return [TSGroupThreadPrefix stringByAppendingString:[groupId base64EncodedString]];
diff --git a/src/Messages/OWSMessageSender.m b/src/Messages/OWSMessageSender.m
index 17086e0fb..08f429883 100644
--- a/src/Messages/OWSMessageSender.m
+++ b/src/Messages/OWSMessageSender.m
@@ -348,16 +348,28 @@ NSString *const OWSMessageSenderInvalidDeviceException = @"InvalidDeviceExceptio
     }];
 
     [completionFuture catchDo:^(id failure) {
-        if ([failure isKindOfClass:[NSError class]]) {
-            return failureHandler(failure);
-        } else if ([failure isKindOfClass:[NSArray class]]) {
+        // failure from toc_thenAll yeilds an array of failed Futures, rather than the future's failure.
+        if ([failure isKindOfClass:[NSArray class]]) {
             NSArray *errors = (NSArray *)failure;
-            // failure from toc_thenAll is a Future, rather than the future's failure.
-            if ([errors.lastObject isKindOfClass:[TOCFuture class]]) {
-                TOCFuture *lastFailure = (TOCFuture *)errors.lastObject;
-                id failureResult = lastFailure.forceGetFailure;
-                if ([failureResult isKindOfClass:[NSError class]]) {
-                    return failureHandler((NSError *)failureResult);
+            for (TOCFuture *failedFuture in errors) {
+                if (!failedFuture.hasFailed) {
+                    // If at least one send succeeded, don't show message as failed.
+                    // Else user will tap-to-resend to all recipients, including those that already received the
+                    // message.
+                    return successHandler();
+                }
+            }
+
+            // At this point, all recipients must have failed.
+            // But we have all this verbose type checking because TOCFuture doesn't expose type information.
+            id lastError = errors.lastObject;
+            if ([lastError isKindOfClass:[TOCFuture class]]) {
+                TOCFuture *failedFuture = (TOCFuture *)lastError;
+                if (failedFuture.hasFailed) {
+                    id failureResult = failedFuture.forceGetFailure;
+                    if ([failureResult isKindOfClass:[NSError class]]) {
+                        return failureHandler((NSError *)failureResult);
+                    }
                 }
             }
         }
@@ -426,8 +438,17 @@ NSString *const OWSMessageSenderInvalidDeviceException = @"InvalidDeviceExceptio
 
             void (^retrySend)() = ^void() {
                 if (remainingAttempts <= 0) {
-                    return failureHandler(error);
+                    NSError *presentedError = error;
+                    if (statuscode == 409) {
+                        presentedError = OWSErrorWithCodeDescription(OWSErrorCodeUntrustedIdentityKey,
+                            NSLocalizedString(@"FAILED_SENDING_BECAUSE_UNTRUSTED_IDENTITY_KEY",
+                                @"action sheet header when re-sending message which failed because of untrusted "
+                                @"identity keys"));
+                    }
+
+                    return failureHandler(presentedError);
                 }
+
                 dispatch_async([OWSDispatch sendingQueue], ^{
                     [self sendMessage:message
                             recipient:recipient
diff --git a/src/Util/OWSError.h b/src/Util/OWSError.h
index 39288cc2b..4614192ad 100644
--- a/src/Util/OWSError.h
+++ b/src/Util/OWSError.h
@@ -11,6 +11,7 @@ typedef NS_ENUM(NSInteger, OWSErrorCode) {
     OWSErrorCodeFailedToEncodeJson = 14,
     OWSErrorCodeFailedToDecodeQR = 15,
     OWSErrorCodePrivacyVerificationFailure = 20,
+    OWSErrorCodeUntrustedIdentityKey = 25,
     OWSErrorCodeFailedToSendOutgoingMessage = 30,
     OWSErrorCodeFailedToDecryptMessage = 100
 };
diff --git a/tests/Messages/OWSMessageSenderTest.m b/tests/Messages/OWSMessageSenderTest.m
index 2d6de79fa..8b725daf6 100644
--- a/tests/Messages/OWSMessageSenderTest.m
+++ b/tests/Messages/OWSMessageSenderTest.m
@@ -1,6 +1,7 @@
 //  Created by Michael Kirk on 10/7/16.
 //  Copyright © 2016 Open Whisper Systems. All rights reserved.
 
+#import "Cryptography.h"
 #import "OWSError.h"
 #import "OWSFakeContactsManager.h"
 #import "OWSFakeContactsUpdater.h"
@@ -8,11 +9,15 @@
 #import "OWSMessageSender.h"
 #import "OWSUploadingService.h"
 #import "TSContactThread.h"
+#import "TSGroupModel.h"
+#import "TSGroupThread.h"
 #import "TSMessagesManager.h"
 #import "TSNetworkManager.h"
 #import "TSOutgoingMessage.h"
 #import "TSStorageManager+keyingMaterial.h"
 #import "TSStorageManager.h"
+#import <AxolotlKit/AxolotlExceptions.h>
+#import <AxolotlKit/SessionBuilder.h>
 #import <XCTest/XCTest.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -393,6 +398,44 @@ NS_ASSUME_NONNULL_BEGIN
     [self waitForExpectationsWithTimeout:5 handler:nil];
 }
 
+- (void)testGroupSend
+{
+    OWSMessageSender *messageSender = self.successfulMessageSender;
+
+
+    NSData *groupIdData = [Cryptography generateRandomBytes:32];
+    SignalRecipient *successfulRecipient =
+        [[SignalRecipient alloc] initWithTextSecureIdentifier:@"successful-recipient-id" relay:nil supportsVoice:YES];
+    SignalRecipient *successfulRecipient2 =
+        [[SignalRecipient alloc] initWithTextSecureIdentifier:@"successful-recipient-id2" relay:nil supportsVoice:YES];
+
+    TSGroupModel *groupModel = [[TSGroupModel alloc]
+        initWithTitle:@"group title"
+            memberIds:[@[ successfulRecipient.uniqueId, successfulRecipient2.uniqueId ] mutableCopy]
+                image:nil
+              groupId:groupIdData];
+    TSGroupThread *groupThread = [TSGroupThread getOrCreateThreadWithGroupModel:groupModel];
+    TSOutgoingMessage *message = [[TSOutgoingMessage alloc] initWithTimestamp:1
+                                                                     inThread:groupThread
+                                                                  messageBody:@"We want punks in the palace."];
+
+    XCTestExpectation *markedAsSent = [self expectationWithDescription:@"markedAsSent"];
+    [messageSender sendMessage:message
+        success:^{
+            if (message.messageState == TSOutgoingMessageStateSent) {
+                [markedAsSent fulfill];
+            } else {
+                XCTFail(@"Unexpected message state");
+            }
+
+        }
+        failure:^(NSError *_Nonnull error) {
+            XCTFail(@"sendMessage should not fail.");
+        }];
+
+    [self waitForExpectationsWithTimeout:5 handler:nil];
+}
+
 - (void)testGetRecipients
 {
     SignalRecipient *recipient =