Re: [exim-dev] Milter api

On 2011-02-03 Todd Lyons <tlyons@???> wrote:
> I really like the power exim has in its macros and string handling,
> but I have always felt like we exclude ourselves from some nice
> software options because we don't support the milter interface.
[...]

Hello,

Disclaimer: I really do not know much about non-exim MTAs and know
milter mainly from wikipedia.

One of the obvious counterarguments is that it complicates things.
With exim4 the basic setup was rather clean, you get one ACL for each
ESMTP verb, routers choose the destination, transports deliver. (The
verify ACL verb and verify_only routers muddy the water a little bit.
acl_smtp_dkim is the odd man.)

Milter being basically a replacement for the ACL system makes it a
strange addition, it seems to be a perfect fit for a stripped down MTA
but with exim it feels like combining a leatherman with a swiss army
knife.

Afaiui milters get passed the message at eached ehlo verb, and can
not only return a status but also modify the contents. I think more or
less the only consistent way to integrate milters would be in adding a
milter verb to the ACL language. And here the fun starts: When is the
milter run? At the start of the ACL, bottom, do I suddenly need to add
a milter statement to every single one of the ACLs (even the ones I am
not currently using)?

cu andreas