In the last two weeks i had a lot of mail which cannot be delivered to the
primary mail-server of the recipient, a lot of them are universities.
Regarding this problem i contacted some postmasters of these domains. At
least one answered, that their primary MX record is for internal use only
and does not accept mail from outside their network and our mail server
should be able to connect to the secondary server which accepts mails. In
all cases i found in the IMail log files that the response from their
servers is:
04:24 09:54 SMTP-(000000BA) 421 SMTP service not available, closing
transmission channel
04:24 09:54 SMTP-(000000BA) SMTP_DELIV_FAILED
04:24 09:54 SMTP-(000000BA) >QUIT
I did some testing on this and found, that sendmail for example handles this
case more "intelligent". I have set up an old UNIX box as relay for imail
where undeliverable mails are sent through. In almost all cases the mails
are delivered to the recipient. The logfiles from this box shows, that
sendmail tries immediatley after receiving the message "421 SMTP service not
available ..." the secondary mail-server of this domain.
Some of you gave me the advice to put these domains in the local hosts file
on my Imail box, what i tried first and worked. But over the last two weeks
i had to add so many records, that this way was not practical for me. The
only way to solve the problem was to setup the unix box, which is not the
most elegant way in my eyes.
Maybe Imail should handle this in the same way as sendmail. It should be
easy to implement this feature in a future release.
Regards,
Heinrich
----- Original Message -----
From: "Len Conrad" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, April 06, 2001 5:42 PM
Subject: Re: [IMail Forum] Problems with mail delivery
>
> >Connected to abc.def.com.
> >Escape character is '^]'.
> >421 SMTP service not available, closing transmission channel
> >Connection closed by foreign host.
>
> 4xx is general category "transient condition, try later". That's not
> your pb, it's theirs.
>
> >The recipient has other mail exchanger, which work without problems, but
> >IMAIL does not use these, our server tries to connect the primary mail
> >server of the recipient.
>
> Of course, that's RFC behavior.
>
>
> >We are using IMAIL 6.06. Is there anything i can do
>
> Tell them to fix the primary MX
>
> >that our server connects to the secondary mail-servers of the
> >recipient? Have i missed
> >something in the manual?
>
> DO NOT TRY THIS AT HOME WITHOUT ADULT SUPERVISION:
>
> I assume you run your own DNS. If not, forget it.
>
> Add this client's zone to your DNS, making/faking your DNS
> authoritative for that zone.
>
> Duplicate all the records for that zone from the "real" DNS to yours,
> EXCEPT the MX records. Use all their MX records, BUt put their
> second MX as first, and their first MX as second.
>
> When Imail asks your DNS for the MX for that domain, your "fake"
> authoritative server will answer with the backup as the primary MX
> and Imail will send the mail to their backup MX.
>
> bitte
>
> Len
>
>
>
> http://MenAndMice.com/DNS-training Austin,TX: 23,24- Apr; SFO,CA; 7,8
> May
> http://BIND8NT.MEIway.com : ISC BIND 8.2.3 "NT3" for NT4 & W2K
> http://IMGate.MEIway.com : Build free, hi-perf, anti-abuse mail gateways
>
>
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