[Mailman-Users] Disabling VERP

Thu Feb 6 01:03:26 CET 2003

Dude!  Awesome explaination - should definitely go into the FAQ...

On Wed, 2003-02-05 at 18:00, Richard Barrett wrote:
> Tom
> 
> 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?
> 
> Regards
> 
> Richard
> 
> 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 
> you.
> 
> 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[49256]: h15Itjct049253:
> >to="|/local/mailman/mail/ma
> >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
> >
> >Followed by:
> >
> >Feb  5 10:55:47 mail2 sm-mta[49261]: h15Itlct049261:
> >from=<listname-bounces at domain.com>, size=1694, class=-30, nrcpts=10,
> >msgid=<BCFA1D35-393B-11D7-AA7A-0003
> >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"
> >log:
> >
> >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?
> >
> >Thanks,
> >
> >Tom
> 
> 
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