The scenario is that there were some users in a Secondary NAB who where not native Notes users and had a separate Internet domain from the Notes users domain. Domino Directory Assistance was set up to include this Secondary NAB but the Directory connector was ignoring the users. The requirement was to have a one time sync from the 3rd party Email system to Exchange.
This was caused by the difference in Internet domain between the two NABs. The Directory connector could not find a match and there was no underlying Domino information to match with either as these were non Notes users. [The mail system in this case was Zimbra, but it would apply for any other email system that was non-Domino.]
The resolution was to edit the Connectors config file with the following:
person-search=(mailaddress=*@tcsindev.com)
The net result was that only entries that matched the above Internet address we synched into Exchange, as the customer wanted.
Please bear in mind that this will only sync NAB entries which match the domain suffix and exclude all else.