About 2 months ago my email address was obtained and I have been getting lots of spam. I have been able to block them using the 'Message Filters' option but these guys are very persistent and continue to change parameters that I have to continually add to my filters. If I could use words in the 'Message Source' in my filters it would solve many of these issues where the sender is the same such as "Sender:marine-embassy-guard-association.googlegroups.com" who has been sending out millions of spam emails for years.