[Mailman-Users] Disabling VERP
r.barrett at openinfo.demon.co.uk
Thu Feb 6 00:00:37 CET 2003
I think there is some confusion here about what is meant by VERP'ed address.
In MM 2.0.x outgoing mail from lists came from the
<listname>-admin at mailman.domain.com alias.
With MM 2.1 outgoing mail from lists normally comes from the
<listname>-bounces at mailman.domain.com alias.
This isn't VERP'ed mail. It is just a change in originator alias which goes
along with some other changes aimed at improving the subsequent handling of
any outbound email from Mailman that bounces.
From your mail log it doesn't appear that the outgoing mail from your
system is being VERP'ed.
With VERP'ing each outgoing mail is specific to the destination email
address and encodes that destination in the originator email alias. So, for
instance, mail to me from a list would be from
<listname>-bounces+r.barrett=openinfo.demon.co.uk at mailman.domain.com. Note
how my email address of r.barrett at opeinfo.demon.co.uk is encoded in that
originator email alias.
The purpose of Verp'ing is to deal with the situation where mail to someone
passes through a MTA that rewrites the destination and that subsequently
bounces. Without VERP'ing the message sent back to mailman has lost the
original destination. Mailman only sees the rewritten destination in the
returned mail and cannot correlate that with any known subscriber of the
list and hence handle the bounce appropriately. With a VERP'ed sender the
original destination is embedded in the address to which the bounced email
is returned. Thus regardless of re-writing of the destination of mail going
out, if it is returned Mailman can reliably identify the subscriber whose
mail is being bounced.
Does that resolve the problem for you?
btw: There would normally be a minimum of four entries in a sendmail log
associated with a message posted to a list if the Mailman local sendmail
instance is alos the SMTP server being used to handle the outgoing mail (I
cannot speak to other MTAs as I do not use them):
1. a 'from' entry for the message being received by the Mailman-local
sendmail instance from some other, relaying, MTA
2. a 'to' entry for sendmail delivering the message to Mailman. This will
have the same message identifier string as 'from' entry (1)
3, a 'from' entry for sendmail sending the posting out to one or more
subscribers. There may be several of these depending on the number of
different domains the outgoing mail is being sent to, the number of list
subscribers and othe factors. If VERP'ing is being applied there will be
one of these entries for each list subscriber.
4. 'to' entries having the same message identifier string(s) as the 'from'
entries (3) for each transfer of the outgoing mail to some other, relaying, MTA
If you have the patience and access you can track mail from source to
destination by matching the seemingly random identifier strings. Its pretty
much a 100% audit trail for all mail that flows. Take a look at the full
headers of this eamil when you get it and you can see how it got from me to
The Mailman post and smtp logs will have entires that tie in with those in
the sendmail logs.
At 19:08 05/02/2003, Tom Maddox wrote:
><snipped massive previous discussion>
> > It looks like the code that initiates VERP'ed return addresses is in
> > $prefix/Mailman/Handlers/ToOutgoing.py and is enacted in
> > $prefix/Mailman/Handlers/SMTPDirect.py.
> > I cannot see anything in those modules that would lead to
> > VERP'ing without
> > one of the appropriate variable being true.
> > What exactly is being logged by your SMTP host for the messages
> > which your
> > users complain of?
>It looks like two messages get logged by sendmail for a given email:
>Feb 5 10:55:46 mail2 sm-mta: h15Itjct049253:
>ilman post listname", ctladdr=<listname at domain.com> (26/0), delay=00:00:01,
>xdelay=00:00:00, mailer=prog, pri=30914, dsn=2.0.0, stat=Sent
>Feb 5 10:55:47 mail2 sm-mta: h15Itlct049261:
>from=<listname-bounces at domain.com>, size=1694, class=-30, nrcpts=10,
>9300CAE4 at domain.com>, proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1]
>In that same time-frame, the following message appears in Mailman's "post"
>Feb 05 10:55:48 2003 (41415) post to listname from listname-bounces at domain.c
>om, size=1694, success
>So, before Mailman posts the message to the list, it's already rewritten the
>header of the message to appear to be from the "-bounces" address.
>Does that shed any light on the issue?
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