Well I removed the if ($toHorde) because basically it just need to do 
it both way according to you. It worked.

Thanks

In this situation the auth is "firstname.lastname" but everywhere in 
horde all property are stored as "firstname.lastname@domain.com" and 
even the first creation of the gallery in ansel store it that way.

If I convert back to the auth username it will brake permission still 
since the owner will be from firstname.lastname@domain.com to only 
firstname.lastname

You are missing the conversion back from the Horde username to the 
auth username.

Just saw I forgot the closing braket for the hook function. The 
function is properly closed.

I use a horde hook to add the @spagi.net to the user if not specified 
the function is as follow

     public function authusername($userId, $toHorde)
     {
         // Example #1: Append the virtual domain to the username only 
if a domain is not already specified.
         // ex. $HTTP_HOST = 'mail.mydomain.com', $userId = 'myname' returns:
         // 'myname@mydomain.com'
         // but $userId = 'myname@mydomain.com' returns self
         $vdomain = preg_replace('|^mail\.|i', '', getenv('HTTP_HOST'));
         $vdomain = Horde_String::lower($vdomain);

         if ($toHorde) {
             if (stripos($userId, '@')){
                 return $userId;
             }else{
                 return $userId . '@' . $vdomain;
             }
         }

It works well in Ansel EXCEPT if I try to change the permission on a 
gallery. Doing so will result that in the SQL table the field 
share_owner will simply record as "@mydomain.com" stripping the user 
and thus removing ownership of the gallery.

On the web interface I tried specifing the owner in the box but doing 
so the changes in the permission aren't recorded. So the only work 
around right now is to make the change in the permission and after 
that go manually in the database in ansel_shares and add the user in 
front of the @domain.com