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

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Gary Bannister
NetAccess Systems Inc.
[log in to unmask]
905-524-2001 x22