hi nikhil ....
I use Pine for mail actually speakin sometime back i had tried to manually configure sendmail which iz very tuff sendmail comes configured in RHL u just have to enable it @ startup services nd configure ur fav mail-client (Kmail , Balsa ...) to use it Pine uses sendmail by default.
rtfm MUA, MTA, MDA concepts first .... :-)
ranjeet
Also for receiving the mail u can use fetchmail and for filtering the mail u can use procmail both r *very* powerful utils :) pls refer
man fetchmail man procmail man procmailex