I have created custom Exchange Address Lists, how can I get my OWA 2007 users to see them in the address book?

The OWA address book shows recipients in the Global Address List and contacts from the Primary contact folder. To extend access to additional Exchange Address Lists, a third-party add-on is required.

One such add-on is Messageware Plus Pack (https://www.messageware.com/), which gives users the ability to see custom Exchange Address Lists, additional personal address lists, SharePoint contact lists, and Public Folder contact lists from a single interface.