Office 365 Migrated Mailbox not showing in Address Book \ GAL for On-premises Users
Issue : Office 365 Migrated Mailbox not showing in Address Book \ GAL for On-premises Users Symptoms : -Unable to find users in GAL \ Address Book -Emails sent failing with NDR (Non Delivery Report) Solution : -Go to Run -> ADSIEdit.msc -Expand Default Naming Context -Navigate to the OU in which the problematical user mailbox is located -Verify the attribute ShowInAddressBook -If this value is Not Set , compare this attribute with a working user and update the attribute ShowInAddressBook -Update the GAL if required by using the below command, Get-GlobalAddressList | Update-GlobalAddressList