Mailenable SMTP settings

[ProWebS]

from the MailEnable Administrator I go to Connectors -> SMTP right click Properties
it shows me the General Tab, and when I try to change to another tab I get the error:
"You need to enter a valid domain name for the Local Domain Name"

whatever I do try to put in the Local Domain box (which by default has "home" in it)
I always get the error "the host name need to be a valid domain name".

Any ideas?