ameritech.net

Is the encryption box checked in your client setup?

not sure what or where that is?

There is a configuration screen where you put in the host names, port numbers, e-mail address and password.  There's usually a checkbox there indicating whether or not your mail server needs your client to encrypt the communications or not.

Take a picture of that screen and post it here (your e-mail address and password blacked out) for review if you wish.