it went wrong where?

I've been running for several months a qmail system on top of what use to be a sendmail. Well during some upgrades on that RH box, apparently the mail system broke. The upgrades apparently upgraded sendmail, and now it wants to be boss again. I can still see qmail processes running, but when I try to send mail from the site it never arrives, and I see a sendmail process spring up but still nothing is sent. I check the /var/spool/mail/root and I'm finding mail in there with this error message as the reason for not being sent:

I've also run a Mail -v and gotten the same response, it looks like this:

Mail -v anti@anti-blank.com
Subject: I hate you
This is to tell you that I hate you so you had better start fixing shit.
.
Cc:
anti@anti-blank.com... Connecting to hoodlum.ghettoweb.net. via esmtp...
220 hoodlum.ghettoweb.net ESMTP Postfix@Ghettoweb Snapshot-20010228 (Even the internet has a ghetto now.)
>>> EHLO srv01.seewhaticando.com
250-hoodlum.ghettoweb.net
250-PIPELINING
250-SIZE 10240000
250-ETRN
250 8BITMIME
>>> MAIL From:<root@srv01.seewhaticando.com> SIZE=118
250 Ok
>>> RCPT To:<anti@anti-blank.com>
450 <root@srv01.seewhaticando.com>: Sender address rejected: Domain not found
anti@anti-blank.com... Deferred: 450 <root@srv01.seewhaticando.com>: Sender address rejected: Domain not found
>>> RSET
250 Ok
Closing connection to hoodlum.ghettoweb.net.
>>> QUIT
221 Bye


I've been hunting around in the system for the past couple of hours tying to see where the upgrade caused things to go so wrong.
But as you can tell with me asking here, it hasn't been much luck. Anyone have any suggestions on this one?