sendmail is sending tons of mail that it seems it shouldn't be. A lot of it looks like

Jun 18 03:24:05 server sendmail[12966]: v5I8O5fW012964: to=<email@address>, ctladdr=<root@server.FQ.DN> (0/0), delay=00:00:00, xdelay=00:00:00, mailer=smtp, pri=121848, relay=anotherserver.FQ.DN [IP address], dsn=2.0.0, stat=Sent (v5I8O5rc013396 Message accepted for delivery)

With the caveat that I've probably already done it, where would you start to look to try to figure out where this mail is being "queued"?