1) Download official version of Thunder Bird Email Client Software at https://www.mozilla.org/en-US/thunderbird/

2) Create a new email account after installation from the downloaded file

3) Select "Skip this and use my existing email account" on prompt

4) Enter "your name", "your email address" & "password", and click "Continue"

5) Select "IMAP" and "Manual Config" on next prompt

6) Key in "mail.yourdomainname.com" for both incoming and outgoing server, change the port,SSL,authentication to autodetect, click "Done" after "Re-test" with no error hit