But, if anything else currently has
the ability to manage customizable helper processes and multiplex jobs
efficiently among them in a way that only requires mime and zip
unpacking to be done onces even if you scan multiple times, I'd be happy
to hear about it.
''Postfix before-queue Milter support
Introduction
Postfix version 2.3 introduces support for the Sendmail version 8
Milter (mail filter) protocol. This protocol is used by applications
that run outside the MTA to inspect SMTP events (CONNECT, DISCONNECT),
SMTP commands (HELO, MAIL FROM, etc.) as well as mail content. All this
happens before mail is queued.
The reason for adding Milter support to Postfix is that there exists a
large collection of applications, not only to block unwanted mail, but
also to verify authenticity (examples: Domain keys identified mail,
SenderID+SPF and Domain keys) or to digitally sign mail (examples:
Domain keys identified mail, Domain keys). Having yet another
Postfix-specific version of all that software is a poor use of human and
system resources.
Postfix version 2.4 implements all the requests of Sendmail version 8
Milter protocols up to version 4, including message body replacement
(body replacement is not available with Postfix version 2.3). See,
however, the workarounds and limitations sections at the end of this
document.
I have been able to get Postfix to do what I want without too much of a
massive effort, whereas when I first tried to use Sendmail I though the
m4 config must be an April Fool's joke. I guess if mail is a large part
of what you do, you can ride over that kind of quirk and become and
"sendmail expert" and get the job done.