Thoughts on MSMilter

Shawn Iverson iversons at
Thu Nov 22 13:29:49 UTC 2018


How much do you know about QMQP?

It looks like I need to do this to send a message to it...I'm going to do
some hacking and see how I can make this work...

Encode a series of safe strings as a netstring representing the message.
Encode the envelope sender the same way (not sure the format)
Encode the original recipients the same way (also not sure the format,
assuming  <email at>)
Send the data to QMQP
Watch for the response, which is either K, Z, or D (decoded from a
Act based on the response K = sent, Z = tempfail, D =permfail

On Wed, Nov 21, 2018 at 10:22 PM Shawn Iverson <iversons at>

> sendmail compatibility interface is not an option, see
> QMQP may be a good option.  I will check into this method....
> On Wed, Nov 21, 2018 at 9:19 PM Mark Sapiro <mark at> wrote:
>> First a big thank you to Shawn for all the work on MSMilter. I think at
>> this point with the merge of
>> <> it is working very well. It
>> also provides a framework for adding even more checks at incoming SMTP
>> time.
>> There is one thing that I think could be improved in the current
>> implementation. The milter is invoked by Postfix via the smtpd_milters
>> configuration on all mail that arrives via SMTP. In most cases, it tells
>> Postfix to DISCARD the message meaning the SMTP client is told the
>> message is accepted but Postfix doesn't queue the message for further
>> processing. The milter in turn has queued the message for MailScanner,
>> and MailScanner processes the message and may queue messages back to be
>> picked up by the milter and redelivered to Postfix.
>> The issue is the milter reinjects the message via SMTP to postfix. This
>> means the milter will be invoked again to process the message it just
>> reinjected. For this reason, the milter just accepts all messages
>> arriving from the local host so they can be processed by Postfix and
>> avoid and endless loop through MailScanner.
>> This all works, except it means that other messages arriving via SMTP
>> from the local host are just accepted by the milter and not seen by
>> MailScanner. This is not a major issue as such messages are usually only
>> generated by trusted users or processes, but this could be avoided if
>> the milter reinjected scanned messages using QMQP or the Postfix
>> sendmail command.
>> --
>> Mark Sapiro <mark at>        The highway is for gamblers,
>> San Francisco Bay Area, California    better use your sense - B. Dylan
>> --
>> MailScanner mailing list
>> mailscanner at
> --
> Shawn Iverson, CETL
> Director of Technology
> Rush County Schools
> 765-932-3901 option 7
> iversons at

Shawn Iverson, CETL
Director of Technology
Rush County Schools
765-932-3901 option 7
iversons at
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