For whatever reason some accounts may not get the MailNickname attribute populated and will cause the issue. Although we set attribute msExchHideFromAddressLists to true, it still shows in the Global Address List (GAL). See notes below.


"Another user attribute that must be populated for msExchHideFromAddressLists to work is the "mailNickname". Set this to their username. If this is not set, then msExchHideFromAddressLists doesn't work correctly."


If missing, add as shown below.


Thanks,

Audel



https://community.spiceworks.com/topic/2003882-attribute-msexchhidefromaddresslists-not-always-hiding-email-in-gal