I'm no expert with E-Smith at all, (in fact my box has died and I havent worked out how to get it up again

) however I had plenty of problems with Email and to be honest it still isn't all resolved, however;
When you say you want to let folk retrieve their email, do you mean you just want users to get mail from any old account using the E-Smith server to connect to their external pop3 accounts. In other words not using the E-Smith server as a mail server?
I had lots of trouble trying to do this but now thankfully I got it sorted.