Take a look at no.Spam.domino .. that allows you to create really simple to really complex mail rules to block stuff like that. You can scan for any field, subject and body texts, email SIGNATURES, mailer types, ip, domain, hostname, username plus it keeps your configuration and notes.ini up to date... there are a bunch of predefined mail rules as well to catch things like poorly formed rfc addresses, invalid message id's, suspicious addresses etc... a free evaluation is available.
http://www.drcc.com/nospamdomino