If you arer using Exim as your MTA, you can use your .forward file to filter your mail. To switch to filter mode, the first line in the file should be ‘# Exim filter’.
These are the relevant anti-spam parts from my .forward:
if $header_Subject: contains " " or $header_Subject: contains "printer toner" or $header_Subject: contains "inkjet refills" or $header_Subject: contains "reduce your debt in 3 minutes" or $header_Subject: contains "enlarge your pen" or $header_Subject: contains "somebody wants to meet you now!" or $header_Subject: contains "free motorola cell phone" or $header_Subject: contains "investments for you" or $header_Subject: contains "free euro!" or $header_Subject: contains "viagra" or $header_Subject: contains "lowest possible prices" or $header_Subject: contains "lenders compete for your business in an auction" or $header_Subject: contains "stock skyrockets 81% ... experts say buy now" or $header_Subject: contains "norton systemworks clearance sale" or $header_Subject: contains "trading strategies with huge potential" or $header_Subject: contains "free online computer training" then save $home/mutt/trash elif $header_From: contains "admin1@wbcnet.net" or $header_From: contains "@e54.org" or $header_From: contains "primeselect@florida.com" or $header_To: contains "prime@florida.com" or $header_From: contains "primeproducts@florida.com" or $header_To: contains "hi@florida.com" or $header_From: contains "joshua629@uole.com" or $header_From: contains "pang_bo@163.com" or $header_From: contains "marya2625649@tiscali.cz" or $header_From: contains "max_statt2123e27@excite.com" or $header_From: contains "o5910@racer.interq.or.jp" or $header_From: contains "gost@devil.interq.or.jp" or $header_From: contains "infowatch@gii.co.jp" or $header_From: contains "angelaf@fantazia.spb.ru" or $header_From: contains "lucretia2378588@pattayacitythailand.com" then save $home/mutt/trash elif $header_From: contains "intervolved.net" and $header_From: contains "valuemail" then save $home/mutt/trash elif $header_Subject: contains "proposal" or $header_Subject: contains "wonlo" or $header_Subject: contains "n`4" or $header_Subject: contains "free" or $header_Subject: contains "lose" or $header_Subject: contains "earn" or $header_Subject: contains "save" or $header_Subject: contains "deal" or $header_Subject: contains "offer" or $header_Subject: contains "complimentary" or $header_Subject: contains "important" or $header_Subject: contains "lowest" or $header_Subject: contains "prices" or $header_Subject: contains "investment" then save $home/mutt/suspicious elif $header_From: contains "wonlo" or $header_From: contains "bulldog" then save $home/mutt/suspicious
Whatever matches the first part goes in the mutt/trash mailbox. You could send it to /dev/null to get rid of it, but just to be safe. After that, it checks for common Spam words and puts them in the mutt/suspicious mailbox which you can check once in a while.