I am having a problem sending Internet E-mail from an Exchange 2000 server
to certain Internet domains. I have traced the problem to an issue with DNS
and MX records: If the MX record points to a CNAME record then mail will
fail (the log states that the host could not be contacted), whereas if the
MX record points to an A record the mail goes through successfully.
I found article Q153001
states that, "RFC 1123 explicitly states that SMTP mail should be addressed
to canonical name hosts. To be canonical, the DNS entry must be an A record
or an MX record. CNAME records are not canonical and should not be mixed
with MX records."
This is fine, but Exchange 5.5 was able to handle this; does anyone know of
a fix for Exchange 2000?