How to fill UserEmail if there is no mail from LDAP?

[magicloud]

Hi,
Just found this exciting tool, but I am not good at perl language, thus I got this problem.
When configuring AD in OTRS, I copied this from the document:
$Self->{'AuthSyncModule::LDAP::UserSyncMap'} = {
# DB -> LDAP
UserFirstname => 'givenName',
UserLastname => 'sn',
UserEmail => 'mail',
};
Here it maps mail field from AD data to UserEmail field in OTRS DB. Well, the AD I am using does not including the mail information. Everyone's mail address is just $cn@company.com.
So I wonder, how to fill UserEmail field in this condition?
Thanks.

[ferrosti]

In case mailaddress is not needed or invalid, one can think of using 'UserPrincipalName' instead.