OE is a HUGE security hole in your system. pick something else, ANYTHING else. please?
sending and recieving mail are completely unrelated, by the way.
your incoming mail server will be something like
pop.sbcglobal.net or mail.mac.com
your outgoing mail will be something like
smtp.mac.com or smtp.sbclogbal.net
(those are the servers for my accts). so: if you've got your incoming server set, but not your outgoing one, your mail will come but not go.
check w/ your mail provider and be sure that you have the correct servers.
as for e-mail clients, I set my mom up on eudora, but she switched back to using the web-based client that her ISP provides. I use mail.app on my mac, so... :/ not gonna be a whole lot of help in that area. sorry.