Hide AD synced users from GAL in O365

Only if msExchHideFromAddressLists is missing from: AD > User > Properties > Attribute Editor

Synchronization Rules Editor > In from AD – User join > Edit > Yes
Precedence: 51 (or higher, up to 99)
Transformations > Add transformation
FlowType: Expression
Target Attribute: msExchHideFromAddressLists
Source:



Save > Yes > OK

PowerShell:



AD > User > Properties > Attribute Editor > msExchAssistantName



PowerShell: