Send/Receive Error message all of a sudden! (Message says ISP doesn't support the connection encrption type).

I have 4 email address with Cox.  All of them have worked with no problems, up until just about an hour ago.  One of the email address is giving me a Send/Receiver error.  It has asked me a few times to put in the password in that "password box" that comes up.  Then I got an error message (when I test "Account Settings") and the message says: 

Send test email message; Your server does not support the connection encryption type you have specified.  Try changing the encryption method.  Contact your ISP Provider for additional assistance.

Note:  My other 3 email addresses are working just fine.  They all have the same Incoming/Outgoing encryptions.

Help???!!!!