diff --git a/api/net/sf/briar/api/db/DatabaseComponent.java b/api/net/sf/briar/api/db/DatabaseComponent.java
index 5a1352e73..4a5da87dd 100644
--- a/api/net/sf/briar/api/db/DatabaseComponent.java
+++ b/api/net/sf/briar/api/db/DatabaseComponent.java
@@ -79,8 +79,9 @@ public interface DatabaseComponent {
 
 	/**
 	 * Generates a batch of messages for the given contact from the given
-	 * collection of requested messages, and returns the IDs of the messages
-	 * added to the bacth.
+	 * collection of requested messages, and returns the IDs of any messages
+	 * that were either added to the batch, or were considered for inclusion
+	 * but are no longer sendable to the contact.
 	 */
 	Collection<MessageId> generateBatch(ContactId c, BatchWriter b,
 			Collection<MessageId> requested) throws DbException, IOException;
diff --git a/components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java b/components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java
index a4cd24cac..996d24e9a 100644
--- a/components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java
+++ b/components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java
@@ -300,13 +300,11 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 					try {
 						Txn txn = db.startTransaction();
 						try {
+							sent = new ArrayList<MessageId>();
 							int capacity = b.getCapacity();
 							Collection<MessageId> sendable =
 								db.getSendableMessages(txn, c, capacity);
-							Iterator<MessageId> it = sendable.iterator();
-							sent = new ArrayList<MessageId>();
-							while(it.hasNext()) {
-								MessageId m = it.next();
+							for(MessageId m : sendable) {
 								byte[] raw = db.getMessage(txn, m);
 								if(!b.writeMessage(raw)) break;
 								bytesSent += raw.length;
@@ -326,9 +324,9 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				} finally {
 					messageStatusLock.readLock().unlock();
 				}
-				BatchId id = b.finish();
 				// Record the contents of the batch, unless it's empty
 				if(sent.isEmpty()) return;
+				BatchId id = b.finish();
 				messageStatusLock.writeLock().lock();
 				try {
 					Txn txn = db.startTransaction();
@@ -357,7 +355,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			if(!containsContact(c)) throw new NoSuchContactException();
 			messageLock.readLock().lock();
 			try {
-				Collection<MessageId> sent;
+				Collection<MessageId> sent, considered;
 				messageStatusLock.readLock().lock();
 				try{
 					subscriptionLock.readLock().lock();
@@ -365,13 +363,20 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 						Txn txn = db.startTransaction();
 						try {
 							sent = new ArrayList<MessageId>();
+							considered = new ArrayList<MessageId>();
 							int bytesSent = 0;
 							for(MessageId m : requested) {
 								byte[] raw = db.getMessageIfSendable(txn, c, m);
-								if(raw == null) continue;
-								if(!b.writeMessage(raw)) break;
-								bytesSent += raw.length;
-								sent.add(m);
+								// If the message is still sendable, try to add
+								// it to the batch. If the batch is full, don't
+								// treat the message as considered, and don't
+								// try to add any further messages.
+								if(raw != null) {
+									if(!b.writeMessage(raw)) break;
+									bytesSent += raw.length;
+									sent.add(m);
+								}
+								considered.add(m);
 							}
 							db.commitTransaction(txn);
 						} catch(DbException e) {
@@ -387,16 +392,16 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				} finally {
 					messageStatusLock.readLock().unlock();
 				}
-				BatchId id = b.finish();
 				// Record the contents of the batch, unless it's empty
-				if(sent.isEmpty()) return sent;
+				if(sent.isEmpty()) return considered;
+				BatchId id = b.finish();
 				messageStatusLock.writeLock().lock();
 				try {
 					Txn txn = db.startTransaction();
 					try {
 						db.addOutstandingBatch(txn, c, id, sent);
 						db.commitTransaction(txn);
-						return sent;
+						return considered;
 					} catch(DbException e) {
 						db.abortTransaction(txn);
 						throw e;
diff --git a/components/net/sf/briar/db/SynchronizedDatabaseComponent.java b/components/net/sf/briar/db/SynchronizedDatabaseComponent.java
index af8f67cd0..3c1aecd15 100644
--- a/components/net/sf/briar/db/SynchronizedDatabaseComponent.java
+++ b/components/net/sf/briar/db/SynchronizedDatabaseComponent.java
@@ -223,23 +223,24 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 					synchronized(subscriptionLock) {
 						Txn txn = db.startTransaction();
 						try {
-							int capacity = b.getCapacity();
-							Collection<MessageId> sendable =
-								db.getSendableMessages(txn, c, capacity);
-							Iterator<MessageId> it = sendable.iterator();
 							Collection<MessageId> sent =
 								new ArrayList<MessageId>();
 							int bytesSent = 0;
-							while(it.hasNext()) {
-								MessageId m = it.next();
+							int capacity = b.getCapacity();
+							Collection<MessageId> sendable =
+								db.getSendableMessages(txn, c, capacity);
+							for(MessageId m : sendable) {
 								byte[] raw = db.getMessage(txn, m);
 								if(!b.writeMessage(raw)) break;
 								bytesSent += raw.length;
 								sent.add(m);
 							}
-							BatchId id = b.finish();
-							if(!sent.isEmpty())
+							// If the batch is not empty, calculate its ID and
+							// record it as outstanding
+							if(!sent.isEmpty()) {
+								BatchId id = b.finish();
 								db.addOutstandingBatch(txn, c, id, sent);
+							}
 							db.commitTransaction(txn);
 						} catch(DbException e) {
 							db.abortTransaction(txn);
@@ -265,19 +266,30 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 						try {
 							Collection<MessageId> sent =
 								new ArrayList<MessageId>();
+							Collection<MessageId> considered =
+								new ArrayList<MessageId>();
 							int bytesSent = 0;
 							for(MessageId m : requested) {
 								byte[] raw = db.getMessageIfSendable(txn, c, m);
-								if(raw == null) continue;
-								if(!b.writeMessage(raw)) break;
-								bytesSent += raw.length;
-								sent.add(m);
+								// If the message is still sendable, try to add
+								// it to the batch. If the batch is full, don't
+								// treat the message as considered, and don't
+								// try to add any further messages.
+								if(raw != null) {
+									if(!b.writeMessage(raw)) break;
+									bytesSent += raw.length;
+									sent.add(m);
+								}
+								considered.add(m);
 							}
-							BatchId id = b.finish();
-							if(!sent.isEmpty())
+							// If the batch is not empty, calculate its ID and
+							// record it as outstanding
+							if(!sent.isEmpty()) {
+								BatchId id = b.finish();
 								db.addOutstandingBatch(txn, c, id, sent);
+							}
 							db.commitTransaction(txn);
-							return sent;
+							return considered;
 						} catch(DbException e) {
 							db.abortTransaction(txn);
 							throw e;