Sebby:daemon.txt in the Mercury 4.51 distribution doesn't appear to be any different to the one in the 4.01 distribution. How does the included Greywall work? There doesn't seem to be anything describing manipulating MercuryS in the docs, so presumably something is new. If that's true, where might we find docs for this improved interface? Is it necessary to have anything more than is contained in the distribution to use the new SMTP server interfaces, or was Greywall developed in testing privately?
GreyWall uses a new event-notification interface for Daemons: in this, every phase of an incoming SMTP transaction can be examined and influenced by a Daemon (or Daemons) in real time; so, if a Daemon doesn't like a particular parameter to MAIL FROM:, it can instruct MercuryS to reject it and blacklist the connection... Or if a Daemon wanted to add a new ESMTP command to MercuryS, it could easily do so by altering the return to EHLO and implementing the command itself.
The Daemon interface has grown hugely from the documentation provided with the program, which is now very old - there 's a whole lot of stuff not covered in there. This is entirely because, like most programmers, I really hate doing documentation, and I'm always so swamped with work that updating these particular docs has just never bubbled to the top of the pot.
I'm not going to make promises I know I probably can't keep, so I'm not going to tell you that I'll get straight onto updating these docs... But I *am* aware that it's something that really *should* be done sooner rather than later, so I'll see if I can make some time (like I say, though, no promises).
Cheers!
-- David --