procmail recepie

Hi All,

This is the first message  i am posting to the mailing list . i hope that i 
would get response.In my scenrio all mails for mydomain.com are forwaded to 
user e.g anything(_at_)mydomain(_dot_)com will be forwarded to user aaqib. The 
mails are coming form all over the internet. what i want is that except from 
yahoo & hotmail. if mails subject is same and sent to many users @mydomain.com 
procmail will delete all the mails. I am newbie to procmail.

Thanks
aaqib