I've noticed that dreamhost seems to be dropping duplicate messages to the catch-all mailbox at my domain. For example, if I do:
[yoda]$ /usr/sbin/sendmail firstname.lastname@example.org email@example.com
From: Testing firstname.lastname@example.org
To: Test1 email@example.com, Test2 firstname.lastname@example.org
Subject: testing if dreamhost drops one of these
...then wait a few seconds, and check my catch-all inbox, only one of the messages will arrive. Has anybody else seen this?