Jared,
Please verify the following setup for your Suddenlink account in Mail:
a) Account type POP3;
b) Your Suddenlink email address;
c) Incoming mailserver is pop.suddenlink.net
d) Outgoing mailserver is smtp.suddenlink.net
e) No UserID / password is required for incoming email, but for outgoing email, Suddenlink requires Password Authentication. For these entries, use your email address (NOT your UserID) and your Password.
mvokla was correct in saying that SSL should be unchecked.
The URL to the Suddenlink Webmail interface is
http://webmail.suddenlink.net (which will resolve automatically to the full URL).
Finally, if you are receiving an error message in response to your attempts to email someone, please include the text of the error message in your post. Certainly, you will need it if you call Suddenlink for assistance. That toll-free number is 1-888-822-5151.