Set your mail server to the server's host name for SMTP/POP3/IMAP (instead of mail.yourdomain.com) and then make sure that your mail client is using the following ports for SSL:
* SMTP - 465
* POP3 - 995
* IMAP - 993
As always you want to make sure that your account name is email@example.com (or user+domain.com) and that you are using authentication on your SMTP server.
(If you do not know your server's SSL hostname, you can see it by logging in to cPanel and then logging at the address bar. It is in the form of: server#.sslpage.com such as server3.sslpage.com)