A few helpful hints to get rid of spammers:

Deleting alone is not effective.
Installing filters is good (my own Internet provider uses Postini filters.  Filters block but don't hit spammers where it hurts them, meaning there is no report of misuse sent to the hosts of the offending accounts.

 Find out how to view full headers on your own email programm, and forward the unsolicited message with full headers to the following addresses. It is a good practice to "x-out" your own email addy in a spam-email you are forwarding to the anti-abuse sites, but keep full subject lines, only x-out your own name, if included in the subject. 

Spamcop is a free service that sends reports to the Internet hosts of accounts who send spam. 
http://spamcop.net

You can register with Spamcop for free, get an ID, and forward all spam messages (full headers) to Spamcop. They automatically trace the originis of the offending spam message, send a report to you, and you click on where to send the report, and it forwards it to the where it really hurts the spammer: their own internet provider. 
Also forward all spam messages to:
UCE@FTC.GOV

This is a US Government address.
They are attempting to determine the extent of email fraud, although I doubt they understand the extent of spam.
For now, they are investigating various fraud and/or scheme scenarios, but they are still asking that ALL spam emails be forwarded to them.

 stock fraud 

If you're solicited with stock/securities promotions, please forward the offending email to: 

enforcement@sec.gov 
cyberfraud@nasaa.org 
isfeedback@nasdaq.com 

These are US government/trading organizations who want to know of any potentially shady deals. You are encouraged to forward any mailings which include stock/securities buy recommendations. 
complaints.detroit@fbi.gov 

Forward all child pornography messages to the FBI at the above address.

 otcfraud@cder.fda.gov

Report drug scams here if directed to a USA addres, the FDA wants to know of potential drug scams.
419.fcd@usss.treas.gov

Report Nigeria-letter scams to the above addy.

 http://www1.ifccfbi.gov/cf1.asp

Direct other internet scam complaints to the above website.
Does it work? I have seen accounts closed because of Spamcop reports -- sometimes in one day!  I have had a chance to testify against a spammer once.  No, reporting abusers does not seem to diminish the number of unsolicited emails I get.  But I believe you can fight spammers: United States internet providers who help them, sometimes unknowingly, will take action against spammers.

A lot of spams however originate in other countries.  I doubt those internet providers close the accounts.  It is sobbering to me, to think anyone would mortgage their home with unknown companies from countries with uncertain legal systems.

Sad thing is, spam works like the drugs: it exists, because some dummies actually pay money to buy anything a spammer offers. 
To me, they start off with a LIE: they LIE about me opting in on their list. I **never** opt in on any lists like that !!!

PS: I have gotten Spam lately from some organization called National Horse Traders. 
Hope no one is doing business with them.

Rena
DreamHorseRanch.com