Author: W B Hacker Date: To: exim users Subject: Re: [exim] Unusual Behavior
Harold Huggins wrote: > SMTP Mail Relay between the local host and remote computer exhibits the
> following behavior:
>
> ~$ telnet dslxxxxxxxx.com 25
> Trying 72.167.97.127...
> Connected to dslxxxxxxxx.com.
> Escape character is '^]'.
> 220-ms.dslxxxxxxxx.com ESMTP Exim 4.69 #1 Wed, 21 Oct 2009 13:34:34 -0700
> 220-We do not authorize the use of this system to transport unsolicited,
> 220 and/or bulk e-mail.
> helo mail.dyndns.com
> 250 ms.dslxxxxxxxx.com Hello xen.thisisnotatrueending.com [216.146.46.13]
> mail from:noone@???
> 250 OK
> rcpt to:support@???
> 421 Unexpected failure, please try later
> rcpt to:admin@???
> 421 Unexpected failure, please try later
> rcpt to:doesnotexist@???
> 421 Unexpected failure, please try later
> rcpt to:fdfd
> 421 Unexpected failure, please try later
> rcpt to:421 Unexpected failure, please try later
> exit 421 Unexpected failure, please try later
> quit 221 ms.dslxxxxxxxx.com closing connection
> Connection closed by foreign host.
>
> For each of the above RCPT TO lines, your server should return a
> 500-level permanent failure error.
Not unless it *IS* a permanent failure.
This says otherwise, and Exim is usually 'very' correct on that score.
e.g - a custom error message might overide default text, and getting the custom
text 'right' is up to the admin. But the number-codes are what they are supposed
to be.
Depending on how strict a test is set up, and how driven, behaviour of this sort
can be the result of inability to access lookup tables or connect to a local DB
or remote BL. If/as/when the resources are once again available, a retry gets
handled accordingly.
> For example:
>
> rcpt to:support@???
> 421 Unexpected failure, please try later
>
> should become:
>
> rcpt to:support@???
> 550 Relay denied
>
Only if it is clear that 'denied' is a certainty.
It may not be getting far enough to ascertain that.
> Of course, your server should accept mail for itself:
>
> rcpt to:admin@???
> 250 OK
>
Not necessarily so it the connection arrives from a forbidden IP (RBL, LBL, or
just plain lacking a valid PTR/MX match. Depends on what the mailadmin
considered important.
My servers will not even complete the telnet response in such cases, so you see
only a blank screen.
> Similarly, and likely related to this behavior, the local server
> transmitting all of the mail it received (potentially forwarding) to
> itself via Outbound, using the sender's address as the From: address:
>
'Might be' a misconfigration. Not able to tell what it was *intended* to do.
You need to contact the mailadmin of the Exim server and ask that (s)he check
the logs, the ~/configure file, DNS availability, perhaps run a few debug traces.
