[exim] Exim4 and pop3

Hi

I am Running Debian 3.1 and Exim4 = i am using a smarthost and am able to
send mail out but i am unabloe to recieve it. I would like to know if there
is anyone that can tell me how to setup ETRN on my server. I would also like
to know which is the best and simplest POP3 package to attach to Exim4 is i
have tried dovecot but its giving me problems. I would also like to why and
how to stop my exim4 sending local mail to my smarthost instead of just
sending it to my local user (/var/mail/$user)

Thank you