Our LISTSERV host has thus far been configured in DNS as an A record,
without a matching MX record.  My understanding is that, although it
doesn't hurt to have an MX record (and it may actually help speed up
the DNS resolver slightly), it is not supposed to be a requirement.

However, one of our list owners recently reported the following error:

Error-Text: Mailer mxnx.berlinetz.de said:
"550 '<[log in to unmask]>SIZE=35126'
sender address target 'LISTSERV.CC.EMORY.EDU' is not a valid e-mail
domain (there is no MX record for it)."

This is the first time I have ever heard of mail being refused due to
not finding an MX record (even though an A record exists).  Has anyone
else seen this?  Should everyone definitively be using MX records now,
or is this just a problem/misconfiguration in the berlinetz.de system?

(The ironic thing is that mxnx.berlinetz.de itself has no MX record.)

Thanks,
Alan

--
Alan S. Dobkin, Operating Systems Analyst
Windows NT Group, Internet/Intranet Services
University Systems Support, Emory University ITD