Advanced alternates regexp

[Andy Repton <mutt@xxxxxxxxxx>]

Hi,

I am trying to figure out how to set my alternates regexp properly. I
have my own domain, and freely generate email addresses for various
purposes, especially web site registrations etc. So my ideal alternates
regexp would be .*@mydomain.

The only problem is that there are also a few email addresses at my
domain that are used by others. So what I really want is an alternates
regexp that matches everything except fred|betty|joe etc

Does anyone know how to do this? I've tried putting ! in front of the
regexp but it doesn't appear to work.

Andy