[Mailman-Users] Disappearing messages

Mark Sapiro mark at msapiro.net
Wed Apr 30 18:24:18 CEST 2014

On 04/30/2014 09:10 AM, Lindsay Haisley wrote:
> And just to be clear here, I don't believe that it's possible for a
> cooperating ESP to make rejection a per-user choice either.  Consider an
> email with multiple recipients served by the same SMTP server.  Because
> of the way SMTP works, all recipients have to be approved or rejected
> _before_ the From body header is received, so instead of rejecting a
> post during the initial transaction with the list server, the post must
> be accepted and then a NDR sent back from the MDA or some other
> component.

Only partially correct.

You can reject based on RCPT TO not being an acceptable address, but as
you say, for DMARC you have to wait until the end of DATA because you
have to have the entire message before you can check the DKIM sig and
the From: alignment.

But you do not have to accept at this point. You can still reject in
response to end of DATA, but if there were multiple RCPT TO addresses,
you can't now go back and just reject some of them.

> I'm not sure how Mailman handles this - if it counts a bounce if the
> initial SMTP transaction is successful but subsequently receives a NDR
> for a recipient address from some other component of the recipient's
> mail system.

Mailman scores bounces both for recipients rejected at SMTP time and for
recognized DSNs (NDRs) later received. That's why the posts from Maiman
have envelope from LISTNAME-bounces (+ possible VERP).

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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