Allow legacyExchangeDN to be modified by Sync

By default, legacyexchangdn is what we call a No-Mod-Attrib. This means it is an attribute that is set when a Destination object is created (ADD), but it is never updated when the object is modified (MOD). This default behavior is recommended in order to avoid changes to the Destination legacyexchangedn which may cause mail delivery errors on the Destination domain.

If you are sure you want to change this default behavior to allow legacyExchangeDN to be modified by a sync, please contact us at support@dirwiz.com for further instruction.

(Support: Reference #3070)