This is only effecting 1 user out of 5 and the other 4 aren't having any issues and all 5 machines are configured the same.
hen using Microsoft Outlook client to access Exchange mailboxes and Inbox, the Outlook does not actually update the all mailboxes and Inbox folder.
Because not all types of data are synchronized with the Exchange server, any complete plan for backing up data must include a provision for backing up the unsynchronized data on users' computers in addition to backing up the Exchange Server database.
Outlook 2016 for Mac stores messages and other items, such as calendar events, contacts, tasks, and notes, as a SQLite database in the /Users/username/Library/Group Containers/UBF8T346G9. These database files can be backed up as part of a procedure that backs up the user's home folder.
Sometimes I can remove the mailbox and re-add it and it starts working but not always.
I have attempted to put Outlook 2013 in cached mode and without and still no change.
Send immediately when connected is in Tools, Options, Mail Setup tab in Outlook 2007 and older.