We have about 10 computers using Bellsouth DSL service, with Bellsouth
hosting our domain. Our Outlook clients are set up for POP3/SMTP using
mail.ourdomain.com.

A few days ago, we began having email problems, especially when we try to
send emails to each other. The returned emails say they are being rejected
by the mailserver as possible spam. One of the returned emails said "Host
blacklisted in sbl-xbl.spamhaus.org.swh.bellsouth.net." It then identified
our public IP address. However, that IP address does not show as
blacklisted on the spamhaus.org website.

I rectified the situation for a couple days by changing the SMTP server from
mail.ourdomain.com to mail.bellsouth.net. That stopped working this
morning. It's as if our mailserver is rejecting mail from itself.

Where do I go from here?
What info have I left out? I'm sure it's a bunch.

jm