After my spam message count started to approach 20 to 30 message per day, I decided to research the subject and discovered that spammers use 'bots that search the web for email addresses kept on public sites. To fight this, the experts recommend changing your email address to a people-readable but not computer-readable address.
For example if your address is firstname.lastname@example.org
, change it to something like "BOB (at) FOOBAR (dot) COM" on any public site that has your address. I did this on the only two sites that had my address: The ARRL mail forwarding service and QRZ.com -- the result: spam almost instantly dropped to two messages per day! Alot of the spam I was receiving did have my call in the address, so the source was not too difficult to figure out but a solution eluded me until I read about this one.