You can easily educate Mail's junk mail filter.

In Mail, highlight a message from the spammer and select Message > Bounce from the menu bar, which will send him a bounce-back message claiming that your address is invalid-which will hopefully convincehim to take you off of his list. Another way to dodge specific emailers is to add them by name to your junk filter. Open Mail > Preferences > Junk Mail, click Advanced, and use the plus-sign icon to add a condition. Use the pull-down menus to configure the new condition as in our screenshot, and the mail might keep coming, but you'll never see it unless you dig into your Spam box. If you use Microsoft Entourage, make similar adjustments under Tools > Junk Email Protection and Tools > Rules. Yet another way is to buy a third-party spaminator such as SpamSieve ($25, http://c-command.com/spamsieve/) and add the spammer to the list of known spammers whose email is blocked automatically.