I am using postfix. is there a benefit to the group based expansion piece you speak of? Postfix is already tied to my ldap instances for user aliases, etc. Andrew Findlay wrote:
Adding the mail attribute is quite simple: define an AUXILIARY object class that permits the attribute, add that to the group entries, and you can then add the mail attribute.
That's what object class 'mailboxRelatedObject' [1] is for.
[1] https://tools.ietf.org/html/draft-stroeder-mailboxrelatedobject
Ciao, Michael.