[Mailman-Users] Rewriting or identifying late bounces

Mark Sapiro mark at msapiro.net
Wed Jul 8 01:20:43 CEST 2009

Stefan Förster wrote:
> some of my list members have a mail address like recipient at example.com
> - nothing special about that. When mail is delivered to their address,
> their ISPs mail server rewrite the address internally to
> recipient at intern.example.com and try to deliver them to the users
> mailbox. If for any reason, e.g. quota, this fails, a NDR/DSN is sent
> with the new name:
> X-Failed-Recipients: recipient at intern.example.com
> Auto-Submitted: auto-replied
> From: Mail Delivery System <Mailer-Daemon at example.com>
> To: invalidlist-bounces at lists.incertum.net
> Subject: Mail delivery failed: returning message to sender
> Message-Id: <E1MOHvF-0007qp-Dc at mbox134.example.com>
> Date: Tue, 07 Jul 2009 23:09:53 +0200
> X-purgate-ID: 149285::1247000993-000022A6-9D72E1E7/0-0/0-18
> This message was created automatically by mail delivery software.
> A message that you sent could not be delivered to one or more of its
> recipients. This is a permanent error. The following address(es) failed:
>   save to inbox
>     generated by recipient at intern.example.com
>     mailbox is full: retry timeout exceeded
> Is there any way to rewrite those addresses or to help Mailman
> identify those bounces correctly?
> And yes, this a pretty stupid thing to do on their ISPs part...

Mailman has a whole host of heuristic recognizers for non-compliant DSNs,
but it doesn't try to guess if a non-member bouncing address might be a
munged version of a member address.

The 'best' solution for recognizing original recipients of bounced
messages is Mailman's VERP like capability. This puts the original
recipient's address in the envelope sender address so the envelope in this
case is from invalidlist-bounces+recipient=example.com at lists.incertum.net.
When the bounce is returned to that address, the MTA delivers it to the
list-bounces address and Mailman recognizes the original recipient as
recipient at example.com from the envelope recipient of the DSN.

The cost of this approach is that Mailman has to send an individual
message to the outgoing MTA for each recipient.

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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