Sendmail is deferring mail

[Sandeep Gupta]

"Erik Max Francis" <max at alcyone.com> wrote in message
news:3DA60E4D.AC120BA1 at alcyone.com...
> A deferred message means that sendmail (not Python) is having some
> difficulty trying to deliver the mail.  The "host map: lookup" message
> suggests that the problem is that MX records for the domain in question
> are not resolving; check to see if DNS is set up properly on the machine
> which is running sendmail.

I ran the following on the sendmail machine:
echo '/mx YYY.com' | /usr/sbin/sendmail -bt -d8.8
and I received the correct MX record.

Any other suggestions?
Thanks