After discovering a DC with the GAL, it appears that Outlook never tries to query for GAL servers again. @dstranathan I think I'm getting closer to an answer.I assume it does this by searching for _ldap._loc SVR records in DNS or it does it via AD CAS Auto Discover foo that Im unaware of. Through this post, I found what looks to be the Offline Address Book .plist file here: /Users/isaachalvorson/Library/Group Containers/UBF8T346G9.In this case your global address book will update each time Send/Receive is pressed. There are a lot of resources to help you become familiar with Office 365.
Outlook 2011 does not use Exchange Cached mode and directly connects to the Global Address Book (GAL) via LDAP connection.
Synchronizing your Outlook (cached) address book with the Global Address book may fix these discrepancies.
Instances of mail that is bounced back to the sender may also be fixed.
All versions: check Download changes since last Send/Receive box.
The generation of the Offline Address Book (OAB) back in Exchange 2010 was based on a schedule set on the OAB’s properties.
It covers only Outlook 2011 (which may have the same behavior as Outlook 2016, but the data caches certainly live in different locations) I tried to flush caches what I think is the correct location for Outlook 2016: ~/Library/Containers/com.microsoft. Outlook/ However, Im not sure if this where the GAL directory settings live. I expect it's a bit more understandable with an on-prem Exchange server.