Ok, everyone can now feel free to continue signing up firstname.lastname@example.org for all those spam lists. The account no longer exists. The password for the nonexistent account, should you require it, is "a3nadotdie", a brief commentary on the account's status as cruft and a slight play on the hostname below.
% ssh athena.dialup.mit.edu
Received disconnect from 18.104.22.168: 15: You are not allowed to log in here: Unknown username
Does that strike anyone else as a bit of a security hole? I mean, giving away the validity of a username?
See also earthdragon's post.