Thomas.Poett@TEAMS (MVP Teams and Cross-Tenant M&A/D Migration Expert Lead)

How to hide and un-hide users from Global Address List (GAL) in Exchange Online if they are AD Connect synchronized Hiding User from GAL isn't possible if those are synchronized form On-Premises Active Directory. The local AD is the leading system for all important attributes, like SMTP, UPN and hiding from GAL. Especially during a cross-tenant migration, you do not want to see not migrated user in the GAL. Those User aren't actively working until their cut-over day. Since the Exchange Online attribute  msExchHideFromAddressList s is an AD on-premises parameter, we have two possible ways hiding user in BME from GAL.   Modify the AD Connect for your teant with a custom rule, by using a extensionAttribute to set the HidefromGAL. In this rule, for users which have an entry in the extensionAttribute, hiding / un-hiding will be controlled by AD Connect This is the best option for Cross-Tenant Migration, if you run 2 or more AD Connect system We direct modif...

SfB On-Premise is making use of the Exchange GAL. If you don't want users or other resources to appear in address book / GAL search in the Skype for Business client there is an easy way. Hiding contacts from GAL, by changing an AD related attribute. This could be e.g. hiding Helpdesk Team Members This is the Exchange attribute for hiding users from the Global Address List (GAL). If this is set to TRUE, which indicates it doesn’t need to appear on the GAL, Lync will also ignore this user for the Address Book. This sets the attribute "msExchHideFromAddressLists" to True. It also clears the attribute "ShowinAddressBook"  This is the Script: $users = Get-CsAdUser -Filter {name -Like "*HelpDesk*"} foreach ($object in $users)     {       Set-ADObject -Add @{msExchHideFromAddressLists=$true} -Identity $object.DistinguishedName       Set-ADObject –clear ShowinAddressBook -Identity $object.Dist...