You will need to ensure that you use the correct mail settings for your POP account setup. If you have a newer account which is using Horde for email, you will have two distinct mail settings which you can use (SSL version and a non-SSL version).
NON-SSL mail settings:
Mail Server Username: Your email address
Incoming Mail Server: mail.yourdomainname
Outgoing Mail Server: mail.yourdomainname (server requires authentication) port 25
Require logon using SPA: Disabled
My server requires authentication: Enabled
Secure Sockets Layer (SSL): Disabled
Incoming server port: 110
Outgoing server port: 25
SSL mail settings:
Mail Server Username: Your email address
Incoming Mail Server: (SSL) the actual mail server name (eg. dpwebcp129.doteasy.com)
Outgoing Mail Server: (SSL) the actual mail server name (eg. dpwebcp129.doteasy.com)
Require logon using SPA: Disabled
My server requires authentication: Enabled
Secure Sockets Layer (SSL): Enabled
Incoming server port: 995
Outgoing server port: 465
If you still experience problems, it would be best to contact Doteasy support directly for additional assistance:
https://www.doteasy.com/ContactUs/SMS3/