On Wed, 14 Jan 1998, David Osborne wrote:
> As at many sites, we have people who mis-configure their mail clients by
> making a mistake in their (sending) mail address.
>
> One such case here involves Pegasus on a PC, posting via a Novell server
> running Mercury. The user has set their address to something like
> "username@???" (name changed to protect the guilty). When
> Mercury tries to send this to one of our mail hubs (which IS
> nottingham.ac.uk), I would expect Exim to reject the message because the
> sender is invalid -- I have sender_verify enabled. However, the message is
> instead rejected with SMTP 421,
> "temporarily unable to verify sender address (try again later)
> <username@???>".
What happens if you run
exim -d -bv username@???
on that system? That should tell you why it is unable to complete the
verification. You might need -d2 or even -d9 to dig out further info.
> Mercury is supposed to retry at a configurable
> interval, defaulting to about an hour, but obviously doesn't understand 421
> (it logs "TCP/IP error") and retries after about 30 seconds.
Not very sensible.
> What can I do to get Exim to return a 5xx permanent error, that the sending
> address is, and will remain, invalid, to stop Mercury retrying?
Arrange that exim -bv manages to complete the verification.
> Looking at the rejectlog, I notice that another message is being retried at
> frequent, short intervals, with a sender address of
> "firstname.surname.@nottingham.ac.uk" (trailing dot before the @) -- the
> relevant firstname.surname alias does exist. The problem is the sending host
> is another system also running Exim 1.73, so it's not just Mercury.
Now that is more worrying. Exim *is* supposed to understand 4xx errors,
and unless the sending system is starting queue runners every 30 seconds
and has a short retry time set, that shouldn't happen. Can you get hold
of the logs from both systems to see what is recorded?
--
Philip Hazel University Computing Service,
ph10@??? New Museums Site, Cambridge CB2 3QG,
P.Hazel@??? England. Phone: +44 1223 334714
--
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