On Tue, 18 Sep 2001 22:32:55 EDT, Gary Bannister <[log in to unmask]>  said:
> We have recently upgraded to the above environment.  The problem is that when sending out mail if Listserv comes across a subscriber's domain that cannot be found (e.g., DNS servers are not reachable) then the error messages below are produced and no messages are sent out.  There is a file (e.g., 12345.mail) that sits in the spool directory indefinitely because of the error.
>
> Has anyone come across this problem?  It appears that some configuration change is need for Sendmail to let it ignore this error and continue processing the list of addresses.
>
> -> RCPT TO:<[log in to unmask]>
> 450 4.7.1 <[log in to unmask]>... Can not check MX records for recipient host S
> ITCOM.NET
> 17 Sep 2001 01:35:27 >>> Error X'00C00E13' enqueuing mail for delivery <<<
> 17 Sep 2001 01:35:27  -> Severity: Error
> 17 Sep 2001 01:35:27  -> Facility: SMTP error code
> 17 Sep 2001 01:35:27  -> Abstract: Unspecified error (450) - See RFC821 et seq

DNS for sitcom.net is provided by ns1.best.com, ns2.best.com, and ns3.best.com,
which however don't realize they are supposed to be providing DNS for it.
The SOA for 'best.com' points you to [log in to unmask], who should be trying to
fix it.

As far as a workaround goes, added 'FEATURE(nocanonify)' to your sendmail.mc
file, re-m4'ing a new .cf file, and restarting Sendmail should help you out
a bit - this will bypass at least some of the DNS checks and maybe defer
the 450 bounce until later (at actual delivery time).  It will also help
speed up the initial submission considerably (I measured a 6X speedup in
the handling of large lists when I originally did it many moons ago).


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                                Valdis Kletnieks
                                Operating Systems Analyst
                                Virginia Tech