[support] Odd Login on my system.

[Skip Taylor]

I'm not sure of the terminology used for this, but I had a login
similar to this on my system.

someone at www.mydomain.com

I understand that it's used to do a shared login from another site
where 'someone' is registered and that's ok.  But the person had *my*
domain after the @ sign, not another domain!  The name before the @
sign wasn't anywhere in my user list.

Any idea what went on here?  The logs aren't very helpful. I'm using
Drupal 4.6.5 and have disabled the Drupal module for now. I think
that's what controls this being available or not.