It looks like that milter-protocol.txt document is slightly out
of date, but it is otherwise pretty accurate.
The only other documentation I know of is the source code
itself. You’d have to trace it back into libmilter/mfdef.h to find
out what each represents (they appear to be “skip” and “insheader”),
and then for the format of the associated messages, check sendmail/milter.c to
see how the MTA will decode them.
(I remember adding “insheader” myself when I still
worked there, and “skip” came sometime later.)
Sent: Thursday, April 22, 2010 2:41 AM
To: dkim-milter general discussion
Subject: Re: [dkim-milter-discuss] dkim-milter protocol documentation
Thanks for the response. I did do a google search before
posting. Most of the resources were about the libmiter package and developing
milters using the milter API. I was interested in the actual communication
between the MTA and a milter. Only related page I could find was,
However, as I mentioned earlier, the response commands such
as 's', 'i' are not documented in this page.
The wikipedia page (http://en.wikipedia.org/wiki/Milter) does
mentions that "documentation of the protocol used for communication
between sendmail and milter processes is not provided. This internal protocol
is subject to changes in new sendmail versions." Probably the responses I
am receiving are introduced in later sendmail versions.
Any other relavent documentation you are aware of will be
On Wed, Apr 21, 2010 at 9:16 PM, Murray S. Kucherawy <firstname.lastname@example.org> wrote:
A Google search for "milter protocol" produced
some highly useful results.
You might also look at the "miltertest" tool in the OpenDKIM package.
It provides a scripting interface to do what you're after.
From: Elanchezhiyan Elango [email@example.com]
Sent: Wednesday, April 21, 2010 5:57 PM
Subject: [dkim-milter-discuss] dkim-milter protocol documentation
I am trying to write a script that would directly communicate to the
dkim-filter process through its socket using the milter protocol. My script
would essentially act like sendmail. In the process I am finding some responses
whose meaning I am not aware of. For example I get responses with command 's',
'i' which don't seem to be documented as a part of milter protocol. Is there a
place where I can find the meaning of these response commands from dkim-milter?
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