when i "change" some settings and save it i get an error:

FAILURE :E-mail settings saved successfully. But error occurred while trying to check connection with mail server - Problem connecting to mailbox

what have i tried.

- change the servername to the ip address

- reset the password from the mail account

- stop and started fetching

- rebooted the server 

- tried an other user

I've also include the support file as well. What can i do more?