[Mimedefang] the right place to put greylist check?

[David F. Skoll]

On Sun, 11 Jan 2004, Mark Sheppard wrote:

> I used to put it right at the end of filter_end.  This should make it
> a little bit more effective because it gives the other checks a chance
> to reject it first, making the greylist a final safety check.  However
> putting it there means that more processing and bandwidth are used and
> the mimedefang process is tied up for longer.  On an overloaded server
> this can matter.  For these reasons I've now moved it to the end of
> filter_recipient for the first recipient.

Be aware of one more factor: Some buggy MTA's (Novell Groupwise for
one, I believe, and ancient versions of SLMail from Seattle Labs) fail
if all RCPT commands are tempfailed, and bounce (rather than queuing
and retrying) the message.

For that reason, I do greylisting at the end of the DATA phase.  However,
I do it in filter_begin before even trying any other tests.  Greylisting
is dirt cheap; might as well do it before moving on to the more expensive
SpamAssassin.

If you know for certain that no-one you care about uses a buggy MTA
that chokes if all RCPT commands are tempfailed, then the best
place is in filter_recipient.

Regards,

David.