Email Antispam Techniques and Email Filtering

Here is a crude procmail recipe that I quickly created (NOT a procmail recipe expert, btw) that has been catching lots of spam (current second after the charset_spam recipe posted earlier):

Code:

:0B
* .*If.you.do.not.wish.to.receive.[further|additional].[email|mailings].*
more_spam

:0B
* You.requested.to.receive.this.mailing
more_spam

:0B
* [Uu]nsubscribe|[Oo][Pp][Tt]-[Oo][Uu][Tt]|[Rr]emoved
* [Cc]lick [Hh]ere
* HTML
more_spam

OBTW, I think I read somewhere that procmail is not case sensitive within regular expressions and I've tested this and it seems they are not. So, the above can be simplified to:

Code:

:0B
* Unsubscribe|Opt-Out|Removed
* Click Here
* HTML
more_spam