Should it be possible to send e-mail to addresses like root@wikipedia.org, postmaster@wikipedia.org, etc? At the moment, sendmail doesn't accept connections except from the local machine on loopback so, eg a theoretical person trying to complain about a spammer sending stuff through clever manipulation of the "e-mail this user" function couldn't reach the customary addresses.
I'm sure it's just a matter of sendmail configuration; I'm just not very up on that because I use qmail on my server.
wikitech-l@lists.wikimedia.org