diff --git a/src/main/java/envoy/server/ConnectionManager.java b/src/main/java/envoy/server/ConnectionManager.java
index 202334f..9dfd56b 100644
--- a/src/main/java/envoy/server/ConnectionManager.java
+++ b/src/main/java/envoy/server/ConnectionManager.java
@@ -1,5 +1,6 @@
 package envoy.server;
 
+import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
@@ -7,6 +8,10 @@ import java.util.Set;
 
 import com.jenkov.nioserver.ISocketIdListener;
 
+import envoy.data.User.UserStatus;
+import envoy.server.database.PersistenceManager;
+import envoy.server.processors.UserStatusChangeProcessor;
+
 /**
  * Project: <strong>envoy-server-standalone</strong><br>
  * File: <strong>ConnectionManager.java</strong><br>
@@ -44,8 +49,16 @@ public class ConnectionManager implements ISocketIdListener {
 
 	@Override
 	public void socketCancelled(long socketId) {
-		if (!pendingSockets.remove(socketId))
+		if (!pendingSockets.remove(socketId)) {
+			// notifying contacts of this users offline-going
+			envoy.server.data.User user = PersistenceManager.getPersistenceManager().getUserById(getUserIdBySocketId(socketId));
+			user.setStatus(UserStatus.OFFLINE);
+			user.setLastSeen(new Date());
+			UserStatusChangeProcessor.updateUserStatus(user);
+
+			// removing the socket
 			sockets.entrySet().stream().filter(e -> e.getValue() == socketId).forEach(e -> sockets.remove(e.getValue()));
+		}
 	}
 
 	@Override
@@ -64,12 +77,21 @@ public class ConnectionManager implements ISocketIdListener {
 	}
 
 	/**
-	 * @param userId the ID of the user registered at the a socket
+	 * @param userId the ID of the user registered at a socket
 	 * @return the ID of the socket
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public long getSocketId(long userId) { return sockets.get(userId); }
 
+	/**
+	 * @param socketId the id of the socket whose User is needed
+	 * @return the userId associated with this socketId
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public long getUserIdBySocketId(long socketId) {
+		return sockets.entrySet().stream().filter((entry) -> entry.getValue().equals(socketId)).findFirst().get().getKey();
+	}
+
 	/**
 	 * @param userId the ID of the user to check for
 	 * @return {@code true} if the user is online
diff --git a/src/main/java/envoy/server/Startup.java b/src/main/java/envoy/server/Startup.java
index 097399e..82d9915 100644
--- a/src/main/java/envoy/server/Startup.java
+++ b/src/main/java/envoy/server/Startup.java
@@ -36,6 +36,7 @@ public class Startup {
 		processors.add(new LoginCredentialProcessor());
 		processors.add(new MessageProcessor());
 		processors.add(new MessageStatusChangeProcessor());
+		processors.add(new UserStatusChangeProcessor());
 		processors.add(new IdGeneratorRequestProcessor());
 		Server server = new Server(8080, () -> new ObjectMessageReader(), new ObjectMessageProcessor(processors));
 
diff --git a/src/main/java/envoy/server/database/PersistenceManager.java b/src/main/java/envoy/server/database/PersistenceManager.java
index 3ec686a..803f177 100644
--- a/src/main/java/envoy/server/database/PersistenceManager.java
+++ b/src/main/java/envoy/server/database/PersistenceManager.java
@@ -108,6 +108,30 @@ public class PersistenceManager {
 		entityManager.getTransaction().commit();
 	}
 
+	/**
+	 * Deletes a {@link User} in the database.
+	 *
+	 * @param user the {@link User} to delete
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public void deleteUser(User user) {
+		entityManager.getTransaction().begin();
+		entityManager.remove(user);
+		entityManager.getTransaction().commit();
+	}
+
+	/**
+	 * Deletes a {@link Message} in the database.
+	 *
+	 * @param message the {@link Message} to delete
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public void deleteMessage(Message message) {
+		entityManager.getTransaction().begin();
+		entityManager.remove(message);
+		entityManager.getTransaction().commit();
+	}
+
 	/**
 	 * Searches for a {@link User} with a specific id.
 	 *
diff --git a/src/main/java/envoy/server/net/ObjectMessageProcessor.java b/src/main/java/envoy/server/net/ObjectMessageProcessor.java
index 226fb69..3bbe43e 100644
--- a/src/main/java/envoy/server/net/ObjectMessageProcessor.java
+++ b/src/main/java/envoy/server/net/ObjectMessageProcessor.java
@@ -33,7 +33,6 @@ public class ObjectMessageProcessor implements IMessageProcessor {
 	 */
 	public ObjectMessageProcessor(Set<ObjectProcessor<?>> processors) { this.processors = processors; }
 
-	@SuppressWarnings("unchecked")
 	@Override
 	public void process(Message message, WriteProxy writeProxy) {
 		try (ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(message.sharedArray, message.offset + 4, message.length - 4))) {
diff --git a/src/main/java/envoy/server/net/ObjectWriteProxy.java b/src/main/java/envoy/server/net/ObjectWriteProxy.java
index 2ec9223..825daeb 100644
--- a/src/main/java/envoy/server/net/ObjectWriteProxy.java
+++ b/src/main/java/envoy/server/net/ObjectWriteProxy.java
@@ -22,7 +22,7 @@ public class ObjectWriteProxy {
 	private final WriteProxy writeProxy;
 
 	/**
-	 * Creates an instance of @link{ObjectWriteProxy}.
+	 * Creates an instance of {@link ObjectWriteProxy}.
 	 *
 	 * @param writeProxy the {@link WriteProxy} to write objects to another client
 	 * @since Envoy Server Standalone v0.1-alpha
diff --git a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index 376989a..acd2b2e 100644
--- a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
+++ b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -10,6 +10,7 @@ import envoy.data.Contacts;
 import envoy.data.LoginCredentials;
 import envoy.data.Message.MessageStatus;
 import envoy.data.User;
+import envoy.data.User.UserStatus;
 import envoy.server.ConnectionManager;
 import envoy.server.ObjectProcessor;
 import envoy.server.data.Message;
@@ -29,31 +30,30 @@ import envoy.server.net.ObjectWriteProxy;
  */
 public class LoginCredentialProcessor implements ObjectProcessor<LoginCredentials> {
 
-	private PersistenceManager	persistenceManager	= PersistenceManager.getPersistenceManager();
+	private PersistenceManager persistenceManager = PersistenceManager.getPersistenceManager();
 
 	@Override
 	public Class<LoginCredentials> getInputClass() { return LoginCredentials.class; }
 
 	@Override
 	public void process(LoginCredentials input, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		UserStatusChangeProcessor.setWriteProxy(writeProxy);
 		System.out.println(String.format("Received login credentials %s from socket ID %d", input, socketId));
 
 		envoy.server.data.User user = getUser(input);
 
 		// Not logged in successfully
-		if (user == null) {
-			return;
-		}
-
+		if (user == null) return;
 		ConnectionManager.getInstance().registerUser(user.getId(), socketId);
 
+		// notifies contacts of this users online-going and updates his status in the
+		// database
+		user.setStatus(UserStatus.ONLINE);
+		UserStatusChangeProcessor.updateUserStatus(user);
+
 		// Create contacts
-		List<User>	users		= PersistenceManager.getPersistenceManager()
-			.getContacts(user)
-			.stream()
-			.map(envoy.server.data.User::toCommonUser)
-			.collect(Collectors.toList());
-		Contacts	contacts	= new Contacts(user.getId(), users);
+		Contacts contacts = new Contacts(user.getId(),
+				user.getContacts().stream().map(envoy.server.data.User::toCommonUser).collect(Collectors.toList()));
 
 		// Complete handshake
 		System.out.println("Sending user...");
@@ -63,8 +63,8 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 		System.out.println("Acquiring pending messages for the client...");
 		List<Message> pendingMessages = PersistenceManager.getPersistenceManager().getUnreadMessages(user);
 		for (Message msg : pendingMessages) {
-			System.out.println("Sending message " + msg.toString());
-			writeProxy.write(socketId, msg);
+			System.out.println("Sending message " + msg.toCommonMessage().toString());
+			writeProxy.write(socketId, msg.toCommonMessage());
 			msg.setReceivedDate(new Date());
 			msg.setStatus(MessageStatus.RECEIVED);
 			PersistenceManager.getPersistenceManager().updateMessage(msg);
@@ -73,21 +73,20 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 
 	private envoy.server.data.User getUser(LoginCredentials credentials) {
 		envoy.server.data.User user;
-		
+
 		if (credentials.isRegistration()) {
 			user = new envoy.server.data.User();
 			user.setName(credentials.getName());
 			user.setLastSeen(new Date());
 			user.setStatus(User.UserStatus.ONLINE);
 			user.setPasswordHash(credentials.getPasswordHash());
+			user.setContacts(PersistenceManager.getPersistenceManager().getContacts(user));
 			persistenceManager.addUser(user);
 		} else {
 			user = persistenceManager.getUserByName(credentials.getName());
 			// TODO: Implement error when user does not exist
-			if (!Arrays.equals(credentials.getPasswordHash(), user.getPasswordHash())) {
-				// TODO: Wrong Password Response
+			if (!Arrays.equals(credentials.getPasswordHash(), user.getPasswordHash())) // TODO: Wrong Password Response
 				return null;
-			}
 		}
 		return user;
 	}
diff --git a/src/main/java/envoy/server/processors/MessageProcessor.java b/src/main/java/envoy/server/processors/MessageProcessor.java
index ad3bc54..0d9a7e6 100644
--- a/src/main/java/envoy/server/processors/MessageProcessor.java
+++ b/src/main/java/envoy/server/processors/MessageProcessor.java
@@ -4,6 +4,7 @@ import java.io.IOException;
 import java.util.Date;
 
 import envoy.data.Message;
+import envoy.event.MessageStatusChangeEvent;
 import envoy.server.ConnectionManager;
 import envoy.server.ObjectProcessor;
 import envoy.server.database.PersistenceManager;
@@ -36,6 +37,7 @@ public class MessageProcessor implements ObjectProcessor<Message> {
 			// Update the message status to RECEIVED
 			message.setReceivedDate(new Date());
 			message.nextStatus();
+			writeProxy.write(connectionManager.getSocketId(message.getSenderId()), new MessageStatusChangeEvent(message));
 		} catch (IOException e) {
 			System.err.println("Recipient online. Failed to send message" + message.getId());
 			e.printStackTrace();
diff --git a/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java b/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java
index 4eec2bc..216e028 100644
--- a/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java
+++ b/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java
@@ -29,8 +29,7 @@ public class MessageStatusChangeProcessor implements ObjectProcessor<MessageStat
 			// any other status than read is not supposed to be sent to the server
 			if (input.get() != MessageStatus.READ) throw new EnvoyException("Message" + input.getId() + "has an invalid status");
 		} catch (EnvoyException e) {
-			e.printStackTrace();
-			return;
+			throw new IOException(e);
 		}
 		ConnectionManager	conMan	= ConnectionManager.getInstance();
 		PersistenceManager	perMan	= PersistenceManager.getPersistenceManager();
@@ -40,6 +39,7 @@ public class MessageStatusChangeProcessor implements ObjectProcessor<MessageStat
 		msg.setReadDate(input.getDate());
 		perMan.updateMessage(msg);
 
-		if (conMan.isOnline(msg.getRecipient().getId())) writeProxy.write(conMan.getSocketId(msg.getRecipient().getId()), input);
+		// Notifies the sender of the message about the status-update to READ
+		if (conMan.isOnline(msg.getSender().getId())) writeProxy.write(conMan.getSocketId(msg.getSender().getId()), input);
 	}
 }
diff --git a/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java b/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
new file mode 100644
index 0000000..63e9798
--- /dev/null
+++ b/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
@@ -0,0 +1,97 @@
+package envoy.server.processors;
+
+import java.io.IOException;
+
+import envoy.data.User.UserStatus;
+import envoy.event.UserStatusChangeEvent;
+import envoy.server.ConnectionManager;
+import envoy.server.ObjectProcessor;
+import envoy.server.data.User;
+import envoy.server.database.PersistenceManager;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * This processor handles incoming {@link UserStatusChangeEvent}.<br>
+ * <br>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>UserStatusChangeProcessor.java</strong><br>
+ * Created: <strong>1 Feb 2020</strong><br>
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+public class UserStatusChangeProcessor implements ObjectProcessor<UserStatusChangeEvent> {
+
+	private static ObjectWriteProxy		writeProxy;
+	private static PersistenceManager	persistenceManager	= PersistenceManager.getPersistenceManager();
+
+	@Override
+	public Class<UserStatusChangeEvent> getInputClass() { return UserStatusChangeEvent.class; }
+
+	@Override
+	public void process(UserStatusChangeEvent input, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		// new status should not equal old status
+		if (input.get().equals(persistenceManager.getUserById(input.getId()).getStatus())) {
+			System.out.println("Received an unnecessary UserStatusChangeEvent");
+			return;
+		}
+		updateUserStatus(input);
+
+	}
+
+	/**
+	 * Sets the {@link UserStatus} for a given user. Both offline contacts and
+	 * currently online contacts are notified.
+	 *
+	 * @param user the {@link UserStatusChangeEvent} that signals the change
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+
+	public static void updateUserStatus(User user) {
+		// handling for newly logged in clients
+		persistenceManager.updateUser(user);
+
+		// handling for contacts that are already online
+		notifyContacts(user);
+	}
+
+	/**
+	 * @param evt the {@link UserStatusChangeEvent}
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public static void updateUserStatus(UserStatusChangeEvent evt) { updateUserStatus(persistenceManager.getUserById(evt.getId())); }
+
+	/**
+	 * notifies active contacts of this {@link User} that his {@link UserStatus} has
+	 * changed
+	 *
+	 * @param evt  the {@link UserStatusChangeEvent} to send to other clients
+	 * @param user the {@link User}
+	 * @throws IOException if sending this update failed for any contact
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	private static void notifyContacts(User user) {
+		UserStatusChangeEvent	evt					= new UserStatusChangeEvent(user.getId(), user.getStatus());
+		ConnectionManager		connectionManager	= ConnectionManager.getInstance();
+		try {
+			for (User contact : user.getContacts())
+				if (connectionManager.isOnline(contact.getId())) writeProxy.write(connectionManager.getSocketId(contact.getId()), evt);
+		} catch (IOException e) {
+			e.printStackTrace();
+			System.err.println("Could not notify online contacts of user " + evt.getId() + " that his status has been changed");
+		}
+	}
+
+	/**
+	 * This method is only called by the LoginCredentialProcessor because every
+	 * user needs to login (open a socket) before changing his status.
+	 * Needed to ensure propagation of events because an uninitialized writeProxy
+	 * would cause problems.
+	 *
+	 * @param writeProxy the writeProxy that is used to send objects back to clients
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public static void setWriteProxy(ObjectWriteProxy writeProxy) { UserStatusChangeProcessor.writeProxy = writeProxy; }
+	// TODO may cause an problem if two clients log in at the same time.
+	// Change Needed.
+}