Message tracking and recall
A general message tracking and recall facility has been implemented. The tracking aspect of this facility conforms to RFC 3885, RFC 3886, and RFC 3887. The recall aspect is implemented as a tracking extension. Additionally, some tracking extensions have been implemented to make it possible for a tracking client to track and recall messages submitted by a non-tracking client.
In order to enable message tracking and recall, a memcache server must be operating, and the
tracking_mode MTA option must be set to
1 to enable use of memcache for message tracking purposes. Which messages get tracking information stored is controlled by various message tracking channel options.