diff --git a/bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxSettingsManager.java b/bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxSettingsManager.java
index 06c383ddb..e2aab69dc 100644
--- a/bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxSettingsManager.java
+++ b/bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxSettingsManager.java
@@ -62,6 +62,8 @@ public interface MailboxSettingsManager {
 
 		/**
 		 * Called when we receive our mailbox's server-supported API versions.
+		 * This happens whenever we successfully check the connectivity of
+		 * our mailbox, so this hook may be called frequently.
 		 *
 		 * @param txn A read-write transaction
 		 */
diff --git a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxUpdateManagerImpl.java b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxUpdateManagerImpl.java
index 7c6ddadfd..dde84ca82 100644
--- a/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxUpdateManagerImpl.java
+++ b/bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxUpdateManagerImpl.java
@@ -216,7 +216,9 @@ class MailboxUpdateManagerImpl implements MailboxUpdateManager,
 				Group contactGroup = getContactGroup(c);
 				LatestUpdate latest =
 						findLatest(txn, contactGroup.getId(), true);
-				// This method should only be called when we have a mailbox
+				// This method should only be called when we have a mailbox,
+				// in which case we should have sent a local update to every
+				// contact
 				if (latest == null) throw new DbException();
 				BdfList body =
 						clientHelper.getMessageAsList(txn, latest.messageId);