Linda Walsh wrote: > I brought this up on this list before, and some > people don't realize that an invalid 'return address' should > be rejected. ... > Accepting bogus email with invalid return paths only helps > spammers and no ISP should accept such... i.e. it says if the > retuen path is not acceptable for some reason, the server MUST reply > with a failure. If the message doesn't have a valid return > address, then an ISP won't be able to comply with the stated > "MUST" requirements. > > In this case, the bounce message comes from the MAILER-DAEMON at > apache.org with a return path of "<>". That isn't a valid return > path.
You would be correct in the case of of a Return-Path of "<[email protected]>", but the null sender "<>" is special in SMTP, and any mail server with the remotest shred of sanity must send postmaster notices using that Return-Path, and must also accept messages with the null sender. Reading back in the thread, this is only present/used on the bounce sent back to the list software by the ASF mail infrastructure when an attempt to send a list mail to you failed: > Return-Path: <> > Received: (qmail 5882 invoked for bounce); 22 Sep 2014 00:57:36 -0000 > Date: 22 Sep 2014 00:57:36 -0000 > From: [email protected] > To: > dev-return-warn-1411347452.lhojmpoahhgeaignmbaf-sa-user=tlinx....@spamassassin.apache.org > Subject: failure notice You don't include the rest of the bounce (and possibly the probe message didn't either), so we can't tell what error was being reported back to the list software - assuming your ISP rejected the original message with an error with any meaning in the first place. Mailing lists like this typically use per-subscriber envelope senders (AKA Return-Path) precisely so they can identify single problem recipients; here's the one on your opening message that I received: Return-Path: <[email protected]> Inspecting a few further messages in the thread shows an incrementing number for that 52870; likely a list message counter or similar. And this looks to be the envelope sender on the probe message sent to you: X-Envelope-From: dev-return-probe-1412233105.cigdbcjjdopojmjdpndi-sa-user=tlinx....@spamassassin.apache.org -kgd
