Hi,
You have to check that the mail server you want to send the outgoing mail is the same server as you use for downloading. Typically it is, but sometimes, the port setting is different (as for my ISP), or the host is different.
My case being a bit weird, I have a different host, port, and also a different user/password for outgoing mail wrt incoming mail.
Also setting up the outgoing mail server let's you check what the remote server accepts in terms of security ('Check what the server supports') that may help you select appropriate login cryptographical features.
hope it helps!