Joe,
I am getting so many spam emails, nowdays I stopped opening those type of suspecious emails.
You would be having spam protector with your email s/w, what s/w are you using?. I think yahoo have a spam blocker option, using which we can block the source before opening that email.
If you really want to block these type of emails, there are so many free spam filter tools are available in the net.
You can try any one of these (small pay)PAMfighter and SpamAgent
These are powerful email monitoring and filtering tool that allows you to get the email you want - and nothing more. It has a comprehensive set of filters (over 1500!) that block spam and unwanted emails - before they reach your inbox.
Archunan
Regards
Archie