It might help to say what error you've encountered? Connection errors, timeouts, etc.?

For incoming it goes through but I can't receive mails, outgoing gives this error " Connection Test failed, connection is unexpectedly closed."

Make sure that the sending on behalf of that domain is supported. Double-check the port, protocol and such, as well as the login credentials. If you double-checked that already and are sure its working then I am out of ideas unfortunately.