problem with sendmail

[Michael Meskes <meskes@debian.org>]

I've set up my sendmail daemon to just forward my mail to my provider's
smart relay host mail.online-club.de. It worked pretty well until earlier
this week. All of a sudden though I get messages like

Deferred: 451 <foo@bar.de>... Deferred by rule.

Obviously no mail goes out. I checked the relay host and sendmail tries to
deliver to post.strato.de. I never even heard about that domain. I just
talked to my provider (since this could have been a name server problem) and
they told me that strato is not their upstream provider. However, it is a
provider too. So all of a sudden my system tries to deliver mail through the
wrong companies smtp host. 

Does anyone have an idea how this could happen? No, I did not change any
software or configuration in between.

Thanks a lot in advance for any idea.

Michael

P.S.: Please CC me on replies.
-- 
Michael Meskes                         | Go SF 49ers!
Th.-Heuss-Str. 61, D-41812 Erkelenz    | Go Rhein Fire!
Tel.: (+49) 2431/72651                 | Use Debian GNU/Linux!
Email: Michael.Meskes@gmx.net          | Use PostgreSQL!