diff --git a/.settings/org.eclipse.jdt.core.prefs b/.settings/org.eclipse.jdt.core.prefs
index cac0df4..db24ee7 100644
--- a/.settings/org.eclipse.jdt.core.prefs
+++ b/.settings/org.eclipse.jdt.core.prefs
@@ -1,7 +1,11 @@
 eclipse.preferences.version=1
 org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
 org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
 org.eclipse.jdt.core.compiler.compliance=1.8
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
 org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
 org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
 org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
diff --git a/src/main/java/envoy/server/ConnectionManager.java b/src/main/java/envoy/server/ConnectionManager.java
index ac4b0c0..0ae8fcc 100644
--- a/src/main/java/envoy/server/ConnectionManager.java
+++ b/src/main/java/envoy/server/ConnectionManager.java
@@ -11,7 +11,7 @@ import com.jenkov.nioserver.ISocketIdListener;
  * Project: <strong>envoy-server-standalone</strong><br>
  * File: <strong>ConnectionManager.java</strong><br>
  * Created: <strong>03.01.2020</strong><br>
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Server Standalone v0.1-alpha
  */
@@ -20,14 +20,14 @@ public class ConnectionManager implements ISocketIdListener {
 	/**
 	 * Contains all socket IDs that have not yet performed a handshake / acquired
 	 * their corresponding user ID.
-	 * 
+	 *
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	private Set<Long> pendingSockets = new HashSet<>();
 
 	/**
 	 * Contains all socket IDs that have acquired a user ID as keys to these IDs.
-	 * 
+	 *
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	private Map<Long, Long> sockets = new HashMap<>();
@@ -53,14 +53,14 @@ public class ConnectionManager implements ISocketIdListener {
 
 	/**
 	 * Associates a socket ID with a user ID.
-	 * 
-	 * @param socketId the socket ID
+	 *
 	 * @param userId   the user ID
+	 * @param socketId the socket ID
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void registerUser(long socketId, long userId) {
-		sockets.put(socketId, userId);
-		pendingSockets.remove(socketId);
+	public void registerUser(long userId, long socketId) {
+		sockets.put(userId, socketId);
+		pendingSockets.remove(userId);
 	}
 
 	/**
diff --git a/src/main/java/envoy/server/MessageProcessor.java b/src/main/java/envoy/server/MessageProcessor.java
deleted file mode 100644
index 3e2f139..0000000
--- a/src/main/java/envoy/server/MessageProcessor.java
+++ /dev/null
@@ -1,32 +0,0 @@
-package envoy.server;
-
-import envoy.data.Message;
-import envoy.server.net.ObjectWriteProxy;
-
-/**
- * This {@link ObjectProcessor} handles incoming {@link Message}s.<br>
- * <br>
- * Project: <strong>envoy-server-standalone</strong><br>
- * File: <strong>MessageProcessor.java</strong><br>
- * Created: <strong>30.12.2019</strong><br>
- *
- * @author Kai S. K. Engelbart
- * @since Envoy Server Standalone v0.1-alpha
- */
-public class MessageProcessor implements ObjectProcessor<Message> {
-
-	@Override
-	public Class<Message> getInputClass() { return Message.class; }
-
-	@Override
-	public void process(Message message, long socketId, ObjectWriteProxy writeProxy) {
-
-		// TODO: Send message to recipient if online
-		ConnectionManager connectionManager = ConnectionManager.getInstance();
-		if (connectionManager.isOnline(message.getRecipientId())) {
-
-		}
-
-		// TODO: Add message to database
-	}
-}
diff --git a/src/main/java/envoy/server/ObjectProcessor.java b/src/main/java/envoy/server/ObjectProcessor.java
index 0221fc0..6828598 100644
--- a/src/main/java/envoy/server/ObjectProcessor.java
+++ b/src/main/java/envoy/server/ObjectProcessor.java
@@ -25,9 +25,10 @@ public interface ObjectProcessor<T> {
 	Class<T> getInputClass();
 
 	/**
-	 * @param input    the request object
-	 * @param socketId the ID of the socket from which the object was received
-	 * @return the response object
+	 * @param input      the request object
+	 * @param socketId   the ID of the socket from which the object was received
+	 * @param writeProxy the object that allows writing to a client
+	 * @throws IOException if something went wrong during processing
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	void process(T input, long socketId, ObjectWriteProxy writeProxy) throws IOException;
diff --git a/src/main/java/envoy/server/Startup.java b/src/main/java/envoy/server/Startup.java
index 58931ff..e2edb6a 100644
--- a/src/main/java/envoy/server/Startup.java
+++ b/src/main/java/envoy/server/Startup.java
@@ -8,6 +8,9 @@ import com.jenkov.nioserver.Server;
 
 import envoy.server.net.ObjectMessageProcessor;
 import envoy.server.net.ObjectMessageReader;
+import envoy.server.processors.EventProcessor;
+import envoy.server.processors.LoginCredentialProcessor;
+import envoy.server.processors.MessageProcessor;
 
 /**
  * Starts the server.<br>
@@ -32,6 +35,7 @@ public class Startup {
 		Set<ObjectProcessor<?>> processors = new HashSet<>();
 		processors.add(new LoginCredentialProcessor());
 		processors.add(new MessageProcessor());
+		processors.add(new EventProcessor());
 		// new PersistenceManager();
 		Server server = new Server(8080, () -> new ObjectMessageReader(), new ObjectMessageProcessor(processors));
 		server.start();
diff --git a/src/main/java/envoy/server/data/Message.java b/src/main/java/envoy/server/data/Message.java
index af7f612..575da6a 100644
--- a/src/main/java/envoy/server/data/Message.java
+++ b/src/main/java/envoy/server/data/Message.java
@@ -12,6 +12,7 @@ import javax.persistence.Temporal;
 import javax.persistence.TemporalType;
 
 import envoy.data.MessageBuilder;
+import envoy.server.database.PersistenceManager;
 
 /**
  * This class serves as a way to let Hibernate communicate with the server
@@ -32,16 +33,15 @@ import envoy.data.MessageBuilder;
 	{ @NamedQuery(
 		query = "SELECT m FROM Message m WHERE m.recipient =:recipient AND m.status = envoy.data.Message$MessageStatus.SENT",
 		name = "getUnreadMessages"
-	),
-			@NamedQuery(
-				query = "SELECT m FROM Message m WHERE m.sender =:sender AND m.status = :status",
-		name = "find read messages"//TODO do we need this namedQuery?
-	), @NamedQuery(query = "SELECT m FROM Message m WHERE m.id = :messageId", name = "get message") }//TODO do we need this namedQuery?
+	), @NamedQuery(
+		query = "SELECT m FROM Message m WHERE m.sender =:sender AND m.status = :status",
+		name = "find read messages"// TODO do we need this namedQuery?
+	), @NamedQuery(query = "SELECT m FROM Message m WHERE m.id = :messageId", name = "getMessageById") }
 )
 public class Message {
 
 	@Id
-	private long								id;
+	private long id;
 
 	@ManyToOne
 	private User sender;
@@ -50,13 +50,13 @@ public class Message {
 	private User recipient;
 
 	@Temporal(TemporalType.TIMESTAMP)
-	private Date								creationDate;
+	private Date creationDate;
 
 	@Temporal(TemporalType.TIMESTAMP)
-	private Date								receivedDate;
+	private Date receivedDate;
 
 	@Temporal(TemporalType.TIMESTAMP)
-	private Date								readDate;
+	private Date readDate;
 
 	private envoy.data.Message.MessageStatus	status;
 	private String								text;
@@ -76,9 +76,14 @@ public class Message {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public Message(envoy.data.Message message) {
-		id		= message.getId();
-		status	= message.getStatus();
-		text	= message.getText();
+		PersistenceManager persMan = PersistenceManager.getPersistenceManager();
+		id				= message.getId();
+		status			= message.getStatus();
+		text			= message.getText();
+		creationDate	= message.getCreationDate();
+		sender			= persMan.getUserById(message.getSenderId());
+		recipient		= persMan.getUserById(message.getRecipientId());
+		// attachment = message.getAttachment().toByteArray();DOES NOT WORK YET
 	}
 
 	/**
diff --git a/src/main/java/envoy/server/data/User.java b/src/main/java/envoy/server/data/User.java
index 40e25c7..5f4e28e 100644
--- a/src/main/java/envoy/server/data/User.java
+++ b/src/main/java/envoy/server/data/User.java
@@ -33,16 +33,42 @@ public class User {
 
 	@Id
 	@GeneratedValue(strategy = GenerationType.IDENTITY)
-	private long						id;
-	private String						name;
-	private byte[]						passwordHash;
+	private long	id;
+	private String	name;
+	private byte[]	passwordHash;
 
 	@Temporal(TemporalType.TIMESTAMP)
 	private Date						lastSeen;
 	private envoy.data.User.UserStatus	status;
 
 	@ElementCollection
-	private List<User>					contacts;
+	private List<User> contacts;
+
+	/**
+	 * Creates an instance of @link{User}.
+	 * Solely used for JPA/ Hibernate
+	 *
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public User() {}
+
+	/**
+	 * Creates an instance of @link{User}.
+	 *
+	 * @param user the {@link envoy.data.User} to convert
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public User(envoy.data.User user) {
+		id		= user.getId();
+		name	= user.getName();
+		status	= user.getStatus();
+	}
+
+	/**
+	 * @return a database {@link User} converted into an {@link envoy.data.User}
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public envoy.data.User toCommonUser() { return new envoy.data.User(this.id, this.name); }
 
 	/**
 	 * @return the id of a {link envoy.data.User}
diff --git a/src/main/java/envoy/server/database/PersistenceManager.java b/src/main/java/envoy/server/database/PersistenceManager.java
index e7c2dc8..fb38a9e 100644
--- a/src/main/java/envoy/server/database/PersistenceManager.java
+++ b/src/main/java/envoy/server/database/PersistenceManager.java
@@ -20,6 +20,21 @@ import envoy.server.data.User;
  */
 public class PersistenceManager {
 
+	private static final PersistenceManager persistenceManager = new PersistenceManager();
+
+	/**
+	 * Creates the singleton instance of the @link{PersistenceManager}.
+	 *
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	private PersistenceManager() {}
+
+	/**
+	 * @return the {@link PersistenceManager} singleton
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public static PersistenceManager getPersistenceManager() { return persistenceManager; }
+
 	private EntityManager entityManager = Persistence.createEntityManagerFactory("envoy").createEntityManager();
 
 	/**
@@ -55,7 +70,7 @@ public class PersistenceManager {
 	public void updateMessage(Message message) { entityManager.unwrap(Session.class).merge(message); }
 
 	/**
-	 * Searches for a user with a specific id.
+	 * Searches for a {@link User} with a specific id.
 	 *
 	 * @param id - the id to search for
 	 * @return the user with the specified id
@@ -63,6 +78,17 @@ public class PersistenceManager {
 	 */
 	public User getUserById(long id) { return (User) entityManager.createNamedQuery("getUserById").setParameter("id", id).getSingleResult(); }
 
+	/**
+	 * Searches for a {@link Message} with a specific id.
+	 *
+	 * @param id - the id to search for
+	 * @return the message with the specified id
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public Message getMessageById(long id) {
+		return (Message) entityManager.createNamedQuery("getMessageById").setParameter("id", id).getSingleResult();
+	}
+
 	/**
 	 * Returns all messages received while being offline.
 	 *
diff --git a/src/main/java/envoy/server/net/ObjectMessageProcessor.java b/src/main/java/envoy/server/net/ObjectMessageProcessor.java
index 47dae57..226fb69 100644
--- a/src/main/java/envoy/server/net/ObjectMessageProcessor.java
+++ b/src/main/java/envoy/server/net/ObjectMessageProcessor.java
@@ -41,17 +41,13 @@ public class ObjectMessageProcessor implements IMessageProcessor {
 			System.out.println("Read object: " + obj.toString());
 
 			// Process object
-			processors.stream()
-				.filter(p -> p.getInputClass().isInstance(obj))
-				.forEach((@SuppressWarnings(
-					"rawtypes"
-				) ObjectProcessor p) -> {
-					try {
-						p.process(p.getInputClass().cast(obj), message.socketId, new ObjectWriteProxy(writeProxy));
-					} catch (IOException e) {
-						e.printStackTrace();
-					}
-				});
+			processors.stream().filter(p -> p.getInputClass().isInstance(obj)).forEach((@SuppressWarnings("rawtypes") ObjectProcessor p) -> {
+				try {
+					p.process(p.getInputClass().cast(obj), message.socketId, new ObjectWriteProxy(writeProxy));
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+			});
 		} catch (IOException | ClassNotFoundException e) {
 			e.printStackTrace();
 		}
diff --git a/src/main/java/envoy/server/net/ObjectWriteProxy.java b/src/main/java/envoy/server/net/ObjectWriteProxy.java
index bd6baf4..2ec9223 100644
--- a/src/main/java/envoy/server/net/ObjectWriteProxy.java
+++ b/src/main/java/envoy/server/net/ObjectWriteProxy.java
@@ -8,6 +8,8 @@ import com.jenkov.nioserver.WriteProxy;
 import envoy.util.SerializationUtils;
 
 /**
+ * This class defines methods to send an object to a client.<br>
+ * <br>
  * Project: <strong>envoy-server-standalone</strong><br>
  * File: <strong>ObjectWriteProxy.java</strong><br>
  * Created: <strong>04.01.2020</strong><br>
@@ -19,8 +21,20 @@ public class ObjectWriteProxy {
 
 	private final WriteProxy writeProxy;
 
+	/**
+	 * Creates an instance of @link{ObjectWriteProxy}.
+	 *
+	 * @param writeProxy the {@link WriteProxy} to write objects to another client
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
 	public ObjectWriteProxy(WriteProxy writeProxy) { this.writeProxy = writeProxy; }
 
+	/**
+	 * @param recipientSocketId the socket id of the recipient
+	 * @param obj               the object to return to the client
+	 * @throws IOException if the serialization of the object failed
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
 	public void write(long recipientSocketId, Object obj) throws IOException {
 		// Create message targeted at the client
 		Message response = writeProxy.getMessage();
diff --git a/src/main/java/envoy/server/processors/EventProcessor.java b/src/main/java/envoy/server/processors/EventProcessor.java
new file mode 100644
index 0000000..58c769f
--- /dev/null
+++ b/src/main/java/envoy/server/processors/EventProcessor.java
@@ -0,0 +1,77 @@
+package envoy.server.processors;
+
+import java.io.IOException;
+
+import envoy.data.Message;
+import envoy.data.Message.MessageStatus;
+import envoy.event.Event;
+import envoy.event.MessageStatusChangeEvent;
+import envoy.exception.EnvoyException;
+import envoy.server.ConnectionManager;
+import envoy.server.ObjectProcessor;
+import envoy.server.database.PersistenceManager;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>EventProcessor.java</strong><br>
+ * Created: <strong>10 Jan 2020</strong><br>
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+public class EventProcessor implements ObjectProcessor<Event<?>> {
+
+	private Event<?> event;
+
+	/**
+	 * Creates an instance of @link{EventProcessor}.
+	 *
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public EventProcessor() {}
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public Class<Event<?>> getInputClass() { return (Class<Event<?>>) event.getClass(); }
+
+	@Override
+	public void process(Event<?> input, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		event = input;
+		if (event instanceof MessageStatusChangeEvent) try {
+			applyMessageStatusChange((MessageStatusChangeEvent) event, writeProxy);
+		} catch (EnvoyException e) {
+			e.printStackTrace();
+		}
+	}
+
+	/**
+	 * Redirects messageStatus changes to the database and to the recipient of the
+	 * {@link Message}.
+	 *
+	 * @param event the {@link MessageStatusChangeEvent} to adjust
+	 * @throws EnvoyException if the {@link Message} has an invalid state
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	private void applyMessageStatusChange(MessageStatusChangeEvent event, ObjectWriteProxy writeProxy) throws EnvoyException {
+		if (!(event.get() == MessageStatus.READ))// check that no invalid MessageStatuses are sent
+			throw new EnvoyException("Message" + event.getId() + "has an invalid status");
+
+		ConnectionManager			conMan	= ConnectionManager.getInstance();
+		PersistenceManager			perMan	= PersistenceManager.getPersistenceManager();
+		envoy.server.data.Message	msg		= perMan.getMessageById(event.getId());
+
+		msg.setStatus(event.get());
+		msg.setReadDate(event.getDate());
+
+		if (conMan.isOnline(msg.getRecipient().getId())) try {
+			writeProxy.write(conMan.getSocketId(msg.getRecipient().getId()), event);
+		} catch (IOException e) {
+			System.err.println("Recipient online. Failed to send MessageStatusChangedEvent at message" + event.getId());
+			e.printStackTrace();
+		}
+		perMan.updateMessage(msg);
+
+	}
+
+}
diff --git a/src/main/java/envoy/server/LoginCredentialProcessor.java b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
similarity index 66%
rename from src/main/java/envoy/server/LoginCredentialProcessor.java
rename to src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index 89261cf..e94ce91 100644
--- a/src/main/java/envoy/server/LoginCredentialProcessor.java
+++ b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -1,11 +1,18 @@
-package envoy.server;
+package envoy.server.processors;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
 
 import envoy.data.Contacts;
 import envoy.data.LoginCredentials;
+import envoy.data.Message.MessageStatus;
 import envoy.data.User;
+import envoy.server.ConnectionManager;
+import envoy.server.ObjectProcessor;
+import envoy.server.data.Message;
+import envoy.server.database.PersistenceManager;
 import envoy.server.net.ObjectWriteProxy;
 
 /**
@@ -42,5 +49,13 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 		writeProxy.write(socketId, user);
 		System.out.println("Sending contacts...");
 		writeProxy.write(socketId, contacts);
+		System.out.println("Sending unread messages and updating them in the database...");
+		List<Message> pendingMessages = PersistenceManager.getPersistenceManager().getUnreadMessages(new envoy.server.data.User(user));
+		pendingMessages.forEach((msg) -> {
+			msg.setReceivedDate(new Date());
+			msg.setStatus(MessageStatus.RECEIVED);
+			PersistenceManager.getPersistenceManager().updateMessage(msg);
+		});
+		writeProxy.write(socketId, pendingMessages);
 	}
 }
diff --git a/src/main/java/envoy/server/processors/MessageProcessor.java b/src/main/java/envoy/server/processors/MessageProcessor.java
new file mode 100644
index 0000000..ce857de
--- /dev/null
+++ b/src/main/java/envoy/server/processors/MessageProcessor.java
@@ -0,0 +1,47 @@
+package envoy.server.processors;
+
+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;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * This {@link ObjectProcessor} handles incoming {@link Message}s.<br>
+ * <br>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>MessageProcessor.java</strong><br>
+ * Created: <strong>30.12.2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+public class MessageProcessor implements ObjectProcessor<Message> {
+
+	@Override
+	public Class<Message> getInputClass() { return Message.class; }
+
+	@Override
+	public void process(Message message, long socketId, ObjectWriteProxy writeProxy) {
+
+		ConnectionManager connectionManager = ConnectionManager.getInstance();
+		message.nextStatus();
+		if (connectionManager.isOnline(message.getRecipientId())) try {// if recipient is online, he receives the message directly
+			writeProxy.write(connectionManager.getSocketId(message.getRecipientId()), message);
+		} catch (IOException e) {
+			System.err.println("Recipient online. Failed to send message" + message.getId());
+			e.printStackTrace();
+		}
+		try {// sender receives confirmation that the server received the message
+			writeProxy.write(connectionManager.getSocketId(message.getSenderId()),
+					new MessageStatusChangeEvent(message.getId(), message.getStatus(), new Date()));
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+		PersistenceManager.getPersistenceManager().addMessage(new envoy.server.data.Message(message));
+	}
+}