Index: bp-activity/bp-activity-notifications.php
===================================================================
--- bp-activity/bp-activity-notifications.php	(revision 6733)
+++ bp-activity/bp-activity-notifications.php	(working copy)
@@ -57,7 +57,11 @@
 	bp_core_add_notification( $activity_id, $receiver_user_id, 'activity', 'new_at_mention', $activity->user_id );
 
 	// Now email the user with the contents of the message (if they have enabled email notifications)
-	if ( 'no' != bp_get_user_meta( $receiver_user_id, 'notification_activity_new_mention', true ) ) {
+	$user_setting_pre_filter = bp_get_user_meta( $receiver_user_id, 'notification_activity_new_mention', true );
+
+	$user_notification_preference = apply_filters( 'bp_activity_at_message_notification_preference', $user_setting_pre_filter, $activity_id, $receiver_user_id, $activity->user_id);
+
+	if ( 'no' != $user_preference ) {
 		$poster_name = bp_core_get_user_displayname( $activity->user_id );
 
 		$message_link  = bp_activity_get_permalink( $activity_id );