i am trying to setup smtp under HOST without any success

can any one tell me what i need to add in those fields

i put mail.domain.net

and in smtp username and password i enter email and password which i usually login with

but keep getting ... i have smarter mail email server

There has been an error trying to send the test email. The error is:
Mailbox unavailable. The server response was: No such user here

this error i get when i click on Test button in Host Settings

Email exists and password is right

maybe i am missing something or putting something wrong

check the email address of the host user!