[Samba] Local vs public domain dns

[Philippe LeCavalier]

Hi,
I recall reading some time ago about the ability to add an alternate domain
name somewhere in the samba (or samba's internal dns backend) config so
that when users open programs like outlook for the first time or are
prompted for sign in they could choose their actual public email domain
rather than the local non-public one. I can't quite come up with the right
terms to google it. Can someone point me in the right direction or am I not
remembering that correctly?
Thanks, Phil