Office 365 outlook address book question

[Maverick964uk]

Question, if the address book has email address entries are these all configured mailboxes?

When a mailbox gets added into 365,new user etc, does it get added to the address book automatically? If so, when mailboxes are deleted are they removed from the global address book too? 

[#2]

@Maverick964uk 

Yes, GAL (Global Address List) is the default of Outlook Address book to search while the address (e.g. user) will be sync by AD\AAD which also means it will update\add\remove from the list when AD\AAD changed