Multiple Logins for Mail

Hi,

I'm a complete newbie when it comes to Apple Mail, and I was wondering whether it's possible to have multiple logins. Here is my situation:

I have a small company with 5 employees who need to access their website e-mail using IMAP. We've been using the Horde web client which is horrendously slow and ugly. I would like for each employee to be able to use Mail to login to their e-mail account and then logout once done. This way employees won't be able to read each other's e-mails. I don't want to have different OS X root level login ID's because then my employees won't have access to all the files on the main admin ID. Unless there's a way around that as well. Any info would be much appreciated!

Thanks,
Alexander