[SOGo] SOGo how can I make the login just "username" instead of email address

["s.sari"]

Hi there,
I just use one domain, so how can I set SOGo to use just "username" instead of 
"usern...@domain.com"
Looking at the SOGo documentation it says this should be possible.
I have changed this setting from YES to NO and restarted the entire server but 
it didn't do anything.
// Must login with full email address
    SOGoForceExternalLoginWithEmail = NO;
Is it possible to do this?
Thanks