If you check this box, source proxy addresses will always overwrite the proxy addresses in the target, replacing whatever values are there, if any. If this box is left unchecked, the source proxy address will only be added to those target objects where this attribute is currently empty.
If you check this box, any TARGET contacts will be converted into mail-enabled users.
For the scope of this feature a Microsoft Exchange Mail Enabled Contact is defined as an Active Directory contact where the LegacyExchangeDN attribute is not null. A contact will be promoted to a user if the primary SMTP address on the a source object matches the external or target email address of the contact. Once the attributes have been stored on the newly created Microsoft Exchange User on the target, the Contact object will be removed from the target. The source User must have a LegacyExchangeDN. The contacts in the source, that will be converted, must be in a different OU than the Target OU selected on the AD Target tab.
This option may not be selected if the setting Create Mail Enabled Users As on the AD Target Options Users tab is set to Contact, or if the source object is already a contact.
If you check this box, any TARGET groups will be converted into mail-enabled users.
Checking this box will cause Directory Sync Pro for Active Directory to only update those objects that are mail-enabled.