"Tickling" Custom Address List Re-evaluation Via Set-Mailbox

In our Exchange environment, we have several custom Address Lists whose membership is determined by the presence of particular strings in CustomAttribute1. In the past, populating this field has been a manual process, accomplished by our Exchange admins entering it via the Exchange Management Console (and, pre-2007, via Active Directory Users & Computers). Recently, we introduced some web-based tools to allow our users to set this themselves. Unfortunately, we soon found that, although the attribute was being set properly, the addresses were not being added to the custom Address Lists, but would if we manually entered the item via EMC or EMS.

The web tool uses ADSI calls to populate the field, bypassing Exchange altogether. Addresses also fail to get added to the custom Address Lists if the custom attribute is populated via LDAP.  The only way that the lists get updated is if Exchange somehow notified that the extension attribute has been changed, thus triggering re-evaluation of custom Address List membership. Happily, we found that issuing a simple "Set-Mailbox " command, with no further arguements or flags, is sufficient to accomplish this.