I noticed from the original post that the user had a Charter account. I myself had the same problem, but I stumbled on the following info from Charter and their settings did the trick. Hopefully, this info can save some frustrations for Charter email users and maybe some of the settings can shed some light for others using the other email providers.
You will need the following information to allow your Smartphone to connect to mobile.charter.net.
Username : firstname.lastname@example.org
Make sure you enter @charter.net after your username or you will be unable to login.
Password: The password you use to login to your e-mail account
SSL : This setting should be on for both SMTP and IMAP
- Port 587
- Note: If you cannot specify a port on your device - try mobile.charter.net:587
If applicable: a login will be required when sending and receiving mail.
- Port 993
- Note: If you cannot specify a port on your device - try mobile.charter.net:993