[Exim] Using Pine with Exim

Hey list, heres a simple question (one so simple, I couldnt figure out)
I have a few users who are starting to use Pine for their email, I've got
them all setup to get their mail from /var/mail/<username>
But, I know that if they ever use Outlook, and dont have it setup to leave a
copy of the message on the server, all their mail will be downloaded, and
Pine's inbox will be empty.
First of all, I want to know if having them pull mail from
/var/mail/username is even a good idea in the first place, but it seems like
the only way to get Pine working.
Second, how would one make Pine keep a local copy for itself in case of an
accidental Outlook download?
I know I should probably direct those Pine questions to the Pine site, but I
felt I might be able to sneak them in here ;)
I also have another question about user authentication.
I had it setup to allow user authentication, using plaintext, so I could
allow users to relay once theyve authenticated. But that method has never
seemed to work.
If someone could give me a breif example on how to accomplish this, I would
be most appreciative!

Thanks a lot guys/gals!

Brent Jones