Can somebody explain to me how to set up Outlook Web Access and Mail??

It works on my iPhone so why won't it connect on my iMac?

Help please!

ETA: Ok, cross posting in GD because I need an answer asap.

OWA and mail are two different things...  OWA is nothing more than going to the website that whoever runs your exchange server has set up for you to use.  Mail, on the other hand, is going to need your ISPs settings (Imap or POP server, SMTP server, authentication) to set up.  I think that Snow Leopard now has exchange support in Mail also, but I haven't used it.  We don't have outside exchange access other than through OWA where I work.