On Thu, Aug 26, 2021 at 01:33:46PM -0400, post...@ptld.com wrote:
> Something else strange, i have been trying to replicate this situation
> using a dummy server to send my server a message with From: and To:
> using the same invalid address. This time i got two reject messages in
> the logs:
>
> NOQUEUE: reject: RCPT from example2.com[IP]: 550 5.1.0
> <u...@example.com>: Sender address rejected: User unknown in virtual
> mailbox table; from=<u...@example.com> to=<u...@example.com> proto=ESMTP
> helo=<example2.com>
>
> NOQUEUE: milter-reject: RCPT from example2.com[IP]: 550 5.5.1 Address
> u...@example.com does not exist; from=<> to=<u...@example.com>
> proto=ESMTP helo=<example2.com>
These are separate mail transactions, and possibly separate SMTP
connections (modulo connection caching on the sender side). You've left
out the connect/disconnect log entries, the process ids, and other
relevant context.
> Now the second reject came from the milter and had from=<> which I
> assume is when it's trying to deliver a postmaster message like a
> rejected backscatter email.
Pronoun trouble. There are two "it"s here, the sending and the
receiving system. The bounce was generated by the sending system after
the receiving system rejected the original message.
> But why would postfix be trying to send a backscatter email when it
> never accepted a message and already rejected the rcpt command?
"It" didn't. See above.
> And yes both of these rejected log lines are part of the same email
> and are one right after the other. The entire transaction was only 4
> log lines, the connect, those two rejects, and then the disconnect
> message.
The envelope sender address is constant in any given transaction.
Since the two log entries show distinct "from=" envelope sender
addresses, they DO NOT belong to the same SMTP transaction.
--
Viktor.
