For anyone else who finds this, you can use any mail client you want. Log in to cpanel. Click Email Accounts. Click Connect Devices to the right of the email account you want to use. Then simply type in the manual settings into your mail client. We recommend using SSL/TLS. Also I usually recommend using the server name instead of the incoming server and outgoing server that cpanel lists. For example it might say mail.krydos.heliohost.org and I think it works better if you put tommy.heliohost.org in your mail client instead. It's possible you could mess up your dns settings, or the SSL certificate on your personal domain could expire. If you use the server name it's less likely to break. Also roundcube and horde webmail are available on port 2096. So if your account is on Tommy you could go to https://tommy.heliohost.org:2096/ to log in directly to your mail account.