iRule to respond to ldap query of external X.500 directory and respond with Primary SMTP, Description, etc.

Trying to clarify and provide more info. User sits on domainA.com User has been migrated to off prem Exchange solution Users exchange organization sync's direcectory's with other external organizations to provide a large address book. Upon migration to the off prem solution users are getting NDR's when trying to resolve users in the large address list. The users are referenced in AD as contacts and not users.

 

I have seen solutions from Microsoft about configuring legacyexchangedn etc. though I am curious if anyone has an irule to provide this information back to the outlook client versus the x.500 address which may be incorrect which an on prem exchange environment still in use as well for "some" users.

 

Even more specifically this is around DISA Defense Enterprise Email so if anyone has run into this I would really appreciate the assistance.

 

Can anyone tell me if it is possible to proxy ldap queries to an external x.500 directory and respond to a the request with values such as primary SMTP address, description rather than the x.500 info that was originally requested?

 

The reason for this request is that my organization has both an on prem and hosted Exchange Services. Because of this, they each have separate address books. 90% of the users utilize the hosted Exchange services and therefor are unable to utilize the on prem address book because it is an external X.500 directory than the hosted Exchange service uses.