diff --git a/Backend/Api/Auth/Check.go b/Backend/Api/Auth/Check.go
new file mode 100644
index 0000000..e503183
--- /dev/null
+++ b/Backend/Api/Auth/Check.go
@@ -0,0 +1,9 @@
+package Auth
+
+import (
+	"net/http"
+)
+
+func Check(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+}
diff --git a/Backend/Api/Routes.go b/Backend/Api/Routes.go
index 7d528ed..5aee439 100644
--- a/Backend/Api/Routes.go
+++ b/Backend/Api/Routes.go
@@ -59,6 +59,8 @@ func InitApiEndpoints(router *mux.Router) {
 	authApi = api.PathPrefix("/auth/").Subrouter()
 	authApi.Use(authenticationMiddleware)
 
+	authApi.HandleFunc("/check", Auth.Check).Methods("GET")
+
 	// Define routes for friends and friend requests
 	authApi.HandleFunc("/friend_requests", Friends.EncryptedFriendRequestList).Methods("GET")
 	authApi.HandleFunc("/friend_request", Friends.CreateFriendRequest).Methods("POST")
diff --git a/mobile/lib/models/messages.dart b/mobile/lib/models/messages.dart
index 0cb0bef..ae0edac 100644
--- a/mobile/lib/models/messages.dart
+++ b/mobile/lib/models/messages.dart
@@ -1,6 +1,5 @@
 import 'dart:convert';
 import 'dart:typed_data';
-import 'package:uuid/uuid.dart';
 import 'package:Envelope/models/conversation_users.dart';
 import 'package:Envelope/models/conversations.dart';
 import 'package:pointycastle/export.dart';
@@ -23,6 +22,7 @@ class Message {
   String senderUsername;
   String associationKey;
   String createdAt;
+  bool failedToSend;
   Message({
     required this.id,
     required this.symmetricKey,
@@ -32,6 +32,7 @@ class Message {
     required this.senderUsername,
     required this.associationKey,
     required this.createdAt,
+    required this.failedToSend,
   });
 
 
@@ -65,6 +66,7 @@ class Message {
         senderUsername: 'Unknown',
         associationKey: json['association_key'],
         createdAt: json['created_at'],
+        failedToSend: false,
     );
   }
 
@@ -151,6 +153,7 @@ class Message {
       'sender_username': senderUsername,
       'association_key': associationKey,
       'created_at': createdAt,
+      'failed_to_send': failedToSend ? 1 : 0,
     };
   }
 
@@ -179,6 +182,7 @@ Future<List<Message>> getMessagesForThread(Conversation conversation) async {
         senderUsername: maps[i]['sender_username'],
         associationKey: maps[i]['association_key'],
         createdAt: maps[i]['created_at'],
+        failedToSend: maps[i]['failed_to_send'] == 1,
     );
   });
 
diff --git a/mobile/lib/utils/storage/conversations.dart b/mobile/lib/utils/storage/conversations.dart
index 749bd67..fa4564e 100644
--- a/mobile/lib/utils/storage/conversations.dart
+++ b/mobile/lib/utils/storage/conversations.dart
@@ -13,63 +13,64 @@ import '/utils/encryption/aes_helper.dart';
 Future<void> updateConversations() async {
     RSAPrivateKey privKey = await getPrivateKey();
 
-    var resp = await http.get(
-            Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/conversations'),
-            headers: {
-                'cookie': await getSessionCookie(),
-            }
-    );
-
-    if (resp.statusCode != 200) {
+    try {
+      var resp = await http.get(
+          Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/conversations'),
+          headers: {
+            'cookie': await getSessionCookie(),
+          }
+      );
+
+      if (resp.statusCode != 200) {
         throw Exception(resp.body);
-    }
+      }
 
-    List<Conversation> conversations = [];
-    List<String> conversationsDetailIds = [];
+      List<Conversation> conversations = [];
+      List<String> conversationsDetailIds = [];
 
-    List<dynamic> conversationsJson = jsonDecode(resp.body);
+      List<dynamic> conversationsJson = jsonDecode(resp.body);
 
-    for (var i = 0; i < conversationsJson.length; i++) {
+      for (var i = 0; i < conversationsJson.length; i++) {
         Conversation conversation = Conversation.fromJson(
-                conversationsJson[i] as Map<String, dynamic>,
-                privKey,
+            conversationsJson[i] as Map<String, dynamic>,
+            privKey,
         );
         conversations.add(conversation);
         conversationsDetailIds.add(conversation.conversationDetailId);
-    }
+      }
 
-    Map<String, String> params = {};
-    params['conversation_detail_ids'] = conversationsDetailIds.join(',');
-    var uri = Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/conversation_details');
-    uri = uri.replace(queryParameters: params);
+      Map<String, String> params = {};
+      params['conversation_detail_ids'] = conversationsDetailIds.join(',');
+      var uri = Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/conversation_details');
+      uri = uri.replace(queryParameters: params);
 
-    resp = await http.get(
-            uri,
-            headers: {
-                'cookie': await getSessionCookie(),
-            }
-    );
+      resp = await http.get(
+          uri,
+          headers: {
+            'cookie': await getSessionCookie(),
+          }
+      );
 
-    if (resp.statusCode != 200) {
+      if (resp.statusCode != 200) {
         throw Exception(resp.body);
-    }
+      }
 
-    final db = await getDatabaseConnection();
+      final db = await getDatabaseConnection();
 
-    List<dynamic> conversationsDetailsJson = jsonDecode(resp.body);
-    for (var i = 0; i < conversationsDetailsJson.length; i++) {
+      List<dynamic> conversationsDetailsJson = jsonDecode(resp.body);
+      for (var i = 0; i < conversationsDetailsJson.length; i++) {
         var conversationDetailJson = conversationsDetailsJson[i] as Map<String, dynamic>;
         var conversation = findConversationByDetailId(conversations, conversationDetailJson['id']);
 
         conversation.name = AesHelper.aesDecrypt(
-                base64.decode(conversation.symmetricKey),
-                base64.decode(conversationDetailJson['name']),
+            base64.decode(conversation.symmetricKey),
+            base64.decode(conversationDetailJson['name']),
         );
 
         await db.insert(
-                'conversations',
-                conversation.toMap(),
-                conflictAlgorithm: ConflictAlgorithm.replace,
+            'conversations',
+            conversation.toMap(),
+            conflictAlgorithm: ConflictAlgorithm.replace,
         );
 
         List<dynamic> usersData = json.decode(
@@ -80,16 +81,19 @@ Future<void> updateConversations() async {
         );
 
         for (var i = 0; i < usersData.length; i++) {
-            ConversationUser conversationUser = ConversationUser.fromJson(
-                usersData[i] as Map<String, dynamic>,
-                conversation.id,
-            );
-
-            await db.insert(
-                'conversation_users',
-                conversationUser.toMap(),
-                conflictAlgorithm: ConflictAlgorithm.replace,
-            );
+          ConversationUser conversationUser = ConversationUser.fromJson(
+              usersData[i] as Map<String, dynamic>,
+              conversation.id,
+          );
+
+          await db.insert(
+              'conversation_users',
+              conversationUser.toMap(),
+              conflictAlgorithm: ConflictAlgorithm.replace,
+          );
         }
+      }
+    } catch (SocketException) {
+      return;
     }
 }
diff --git a/mobile/lib/utils/storage/database.dart b/mobile/lib/utils/storage/database.dart
index 41419e5..86e2a31 100644
--- a/mobile/lib/utils/storage/database.dart
+++ b/mobile/lib/utils/storage/database.dart
@@ -65,7 +65,8 @@ Future<Database> getDatabaseConnection() async {
                                 sender_id TEXT,
                                 sender_username TEXT,
                                 association_key TEXT,
-                                created_at TEXT
+                                created_at TEXT,
+                                failed_to_send INTEGER
                         );
                         ''');
 
diff --git a/mobile/lib/utils/storage/friends.dart b/mobile/lib/utils/storage/friends.dart
index a4fc827..f3347cb 100644
--- a/mobile/lib/utils/storage/friends.dart
+++ b/mobile/lib/utils/storage/friends.dart
@@ -10,17 +10,18 @@ import '/utils/storage/session_cookie.dart';
 import '/utils/encryption/aes_helper.dart';
 
 Future<void> updateFriends() async {
-    RSAPrivateKey privKey = await getPrivateKey();
+  RSAPrivateKey privKey = await getPrivateKey();
 
+  try {
     var resp = await http.get(
-            Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/friend_requests'),
-            headers: {
-                'cookie': await getSessionCookie(),
-            }
+        Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/friend_requests'),
+        headers: {
+          'cookie': await getSessionCookie(),
+        }
     );
 
     if (resp.statusCode != 200) {
-        throw Exception(resp.body);
+      throw Exception(resp.body);
     }
 
     List<Friend> friends = [];
@@ -29,14 +30,14 @@ Future<void> updateFriends() async {
     List<dynamic> friendsRequestJson = jsonDecode(resp.body);
 
     for (var i = 0; i < friendsRequestJson.length; i++) {
-        friends.add(
-                Friend.fromJson(
-                        friendsRequestJson[i] as Map<String, dynamic>,
-                        privKey,
-                        )
-        );
-
-        friendIds.add(friends[i].friendId);
+      friends.add(
+          Friend.fromJson(
+              friendsRequestJson[i] as Map<String, dynamic>,
+              privKey,
+          )
+      );
+
+      friendIds.add(friends[i].friendId);
     }
 
     Map<String, String> params = {};
@@ -45,35 +46,39 @@ Future<void> updateFriends() async {
     uri = uri.replace(queryParameters: params);
 
     resp = await http.get(
-            uri,
-            headers: {
-                'cookie': await getSessionCookie(),
-            }
+        uri,
+        headers: {
+          'cookie': await getSessionCookie(),
+        }
     );
 
     if (resp.statusCode != 200) {
-        throw Exception(resp.body);
+      throw Exception(resp.body);
     }
 
     final db = await getDatabaseConnection();
 
     List<dynamic> friendsJson = jsonDecode(resp.body);
     for (var i = 0; i < friendsJson.length; i++) {
-        var friendJson = friendsJson[i] as Map<String, dynamic>;
-        var friend = findFriendByFriendId(friends, friendJson['id']);
+      var friendJson = friendsJson[i] as Map<String, dynamic>;
+      var friend = findFriendByFriendId(friends, friendJson['id']);
 
-        friend.username = AesHelper.aesDecrypt(
-                base64.decode(friend.friendSymmetricKey),
-                base64.decode(friendJson['username']),
-        );
+      friend.username = AesHelper.aesDecrypt(
+          base64.decode(friend.friendSymmetricKey),
+          base64.decode(friendJson['username']),
+      );
 
-        friend.asymmetricPublicKey = friendJson['asymmetric_public_key'];
+      friend.asymmetricPublicKey = friendJson['asymmetric_public_key'];
 
-        await db.insert(
-                'friends',
-                friend.toMap(),
-                conflictAlgorithm: ConflictAlgorithm.replace,
-        );
+      await db.insert(
+          'friends',
+          friend.toMap(),
+          conflictAlgorithm: ConflictAlgorithm.replace,
+      );
     }
+
+  } catch (SocketException) {
+    return;
+  }
 }
 
diff --git a/mobile/lib/utils/storage/messages.dart b/mobile/lib/utils/storage/messages.dart
index 33c13e6..ea9457f 100644
--- a/mobile/lib/utils/storage/messages.dart
+++ b/mobile/lib/utils/storage/messages.dart
@@ -52,12 +52,16 @@ Future<void> updateMessageThread(Conversation conversation, {RSAPrivateKey? priv
 }
 
 Future<void> updateMessageThreads({List<Conversation>? conversations}) async {
-  RSAPrivateKey privKey = await getPrivateKey();
+  try {
+    RSAPrivateKey privKey = await getPrivateKey();
 
-  conversations ??= await getConversations();
+    conversations ??= await getConversations();
 
-  for (var i = 0; i < conversations.length; i++) {
-    await updateMessageThread(conversations[i], privKey: privKey);
+    for (var i = 0; i < conversations.length; i++) {
+      await updateMessageThread(conversations[i], privKey: privKey);
+    }
+  } catch(SocketException) {
+    return;
   }
 }
 
@@ -74,7 +78,6 @@ Future<void> sendMessage(Conversation conversation, String data) async {
 
   ConversationUser currentUser = await getConversationUserByUsername(conversation, username);
 
-
   Message message = Message(
       id: messageDataId,
       symmetricKey: '',
@@ -82,31 +85,44 @@ Future<void> sendMessage(Conversation conversation, String data) async {
       senderId: userId,
       senderUsername: username,
       data: data,
-      createdAt: DateTime.now().toIso8601String(),
       associationKey: currentUser.associationKey,
+      createdAt: DateTime.now().toIso8601String(),
+      failedToSend: false,
   );
 
   final db = await getDatabaseConnection();
 
-  print(await db.query('messages'));
-
   await db.insert(
       'messages',
       message.toMap(),
       conflictAlgorithm: ConflictAlgorithm.replace,
   );
 
-  String messageJson = await message.toJson(conversation, messageDataId);
-
-  final resp = await http.post(
-      Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/message'),
-      headers: <String, String>{
-        'Content-Type': 'application/json; charset=UTF-8',
-        'cookie': await getSessionCookie(),
-      },
-      body: messageJson,
-  );
-
-  // TODO: If statusCode not successfull, mark as needing resend
-  print(resp.statusCode);
+  String sessionCookie = await getSessionCookie();
+
+  message.toJson(conversation, messageDataId)
+      .then((messageJson) {
+        return http.post(
+            Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/message'),
+            headers: <String, String>{
+              'Content-Type': 'application/json; charset=UTF-8',
+              'cookie': sessionCookie,
+            },
+            body: messageJson,
+        );
+      })
+      .then((resp) {
+        if (resp.statusCode != 200) {
+          throw Exception('Unable to send message');
+        }
+      })
+      .catchError((exception) {
+        message.failedToSend = true;
+        db.update(
+            'messages',
+            message.toMap(),
+            where: 'id = ?',
+            whereArgs: [message.id],
+        );
+      });
 }
diff --git a/mobile/lib/views/authentication/login.dart b/mobile/lib/views/authentication/login.dart
index 9802423..7c60879 100644
--- a/mobile/lib/views/authentication/login.dart
+++ b/mobile/lib/views/authentication/login.dart
@@ -67,7 +67,7 @@ Future<LoginResponse> login(context, String username, String password) async {
   setPrivateKey(rsaPriv);
 
   final preferences = await SharedPreferences.getInstance();
-  preferences.setBool('islogin', true);
+  preferences.setString('logged_in_at', (DateTime.now()).toIso8601String());
   preferences.setString('userId', response.userId);
   preferences.setString('username', response.username);
   preferences.setString('asymmetricPublicKey', response.asymmetricPublicKey);
diff --git a/mobile/lib/views/main/conversation_detail.dart b/mobile/lib/views/main/conversation_detail.dart
index c3f0bb4..f00e84e 100644
--- a/mobile/lib/views/main/conversation_detail.dart
+++ b/mobile/lib/views/main/conversation_detail.dart
@@ -54,6 +54,32 @@ class _ConversationDetailState extends State<ConversationDetail> {
     setState(() {});
   }
 
+  Widget usernameOrFailedToSend(int index) {
+    if (messages[index].senderUsername != username) {
+      return Text(messages[index].senderUsername);
+    }
+
+    if (messages[index].failedToSend) {
+      return Row(
+          mainAxisAlignment: MainAxisAlignment.end,
+          children: const <Widget>[
+            Icon(
+                Icons.warning_rounded,
+                color: Colors.red,
+                size: 20,
+            ),
+            Text(
+                'Failed to send',
+                style: TextStyle(color: Colors.red, fontSize: 12),
+                textAlign: TextAlign.right,
+            ),
+          ],
+      );
+    }
+
+    return const SizedBox.shrink();
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -102,7 +128,7 @@ class _ConversationDetailState extends State<ConversationDetail> {
                           reverse: true,
                           itemBuilder: (context, index) {
                             return Container(
-                                padding: const EdgeInsets.only(left: 14,right: 14,top: 0,bottom: 0),
+                                padding: const EdgeInsets.only(left: 14,right: 14,top: 0,bottom: 10),
                                 child: Align(
                                     alignment: (
                                         messages[index].senderUsername == username ?
@@ -126,9 +152,7 @@ class _ConversationDetailState extends State<ConversationDetail> {
                                             padding: const EdgeInsets.all(12),
                                             child: Text(messages[index].data, style: const TextStyle(fontSize: 15)),
                                           ),
-                                          messages[index].senderUsername != username ?
-                                            Text(messages[index].senderUsername) :
-                                            const SizedBox.shrink(),
+                                          usernameOrFailedToSend(index),
                                           Text(
                                             convertToAgo(messages[index].createdAt),
                                             textAlign: TextAlign.left,
diff --git a/mobile/lib/views/main/home.dart b/mobile/lib/views/main/home.dart
index 06c6295..f7a0d6d 100644
--- a/mobile/lib/views/main/home.dart
+++ b/mobile/lib/views/main/home.dart
@@ -1,11 +1,14 @@
 import 'package:flutter/material.dart';
 import 'package:shared_preferences/shared_preferences.dart';
+import 'package:http/http.dart' as http;
+import 'package:flutter_dotenv/flutter_dotenv.dart';
 import '/views/main/conversation_list.dart';
 import '/views/main/friend_list.dart';
 import '/views/main/profile.dart';
 import '/utils/storage/friends.dart';
 import '/utils/storage/conversations.dart';
 import '/utils/storage/messages.dart';
+import '/utils/storage/session_cookie.dart';
 import '/models/conversations.dart';
 import '/models/friends.dart';
 
@@ -53,12 +56,46 @@ class _HomeState extends State<Home> {
     });
   }
 
-  // TODO: Do server GET check here
-  Future checkLogin() async {
+  Future<void> checkLogin() async {
     SharedPreferences preferences = await SharedPreferences.getInstance();
-    if (preferences.getBool('islogin') != true) {
+
+    var loggedInTime = preferences.getString('logged_in_at');
+    if (loggedInTime == null) {
+      preferences.remove('logged_in_at');
+      preferences.remove('username');
+      preferences.remove('userId');
+      preferences.remove('asymmetricPublicKey');
       Navigator.pushNamedAndRemoveUntil(context, '/landing', ModalRoute.withName('/landing'));
+      return;
+    }
+
+    DateTime loggedInAt = DateTime.parse(loggedInTime);
+    bool isAfter = loggedInAt.isAfter((DateTime.now()).add(const Duration(hours: 12)));
+    int statusCode = 200;
+
+    try {
+      var resp = await http.get(
+          Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/auth/check'),
+          headers: {
+            'cookie': await getSessionCookie(),
+          }
+      );
+      statusCode = resp.statusCode;
+    } catch(SocketException) {
+      if (!isAfter) {
+        return;
+      }
     }
+
+    if (!isAfter && statusCode == 200) {
+      return;
+    }
+
+    preferences.remove('logged_in_at');
+    preferences.remove('username');
+    preferences.remove('userId');
+    preferences.remove('asymmetricPublicKey');
+    Navigator.pushNamedAndRemoveUntil(context, '/landing', ModalRoute.withName('/landing'));
   }
 
   void _onItemTapped(int index) {
diff --git a/mobile/lib/views/main/profile.dart b/mobile/lib/views/main/profile.dart
index 64d65ff..ccc84d5 100644
--- a/mobile/lib/views/main/profile.dart
+++ b/mobile/lib/views/main/profile.dart
@@ -37,7 +37,9 @@ class _ProfileState extends State<Profile> {
                                                                                 onTap: () async {
                                                                                     deleteDb();
                                                                                     final preferences = await SharedPreferences.getInstance();
-                                                                                    preferences.setBool('islogin', false);
+                                                                                    preferences.remove('logged_in_at');
+                                                                                    preferences.remove('username');
+                                                                                    preferences.remove('userId');
                                                                                     preferences.remove(rsaPrivateKeyName);
                                                                                     Navigator.pushNamedAndRemoveUntil(context, '/landing', ModalRoute.withName('/landing'));
                                                                                 },