DNS problem in Entourage

[pammm56]

Since updating Microsoft Office 2004 I've been getting a lot of these
error messages:

[TEMPFAIL] destination not valid within DNS

Cannot send mail. The SMTP server does not recognize any of the authentication methods supported >by Entourage. Try changing the SMTP authentication options in Account settings or contact your >network administrator.

Error: -17092

I don't have anything checked in the SMTP advanced sending options. I
can send the mail directly from the Comcast.net website mail pages so
it seems something in Entourage rather than Comcast, doesn't it?