I manage an on premise Exchange 2013 environment with a single server hosting all the roles and running the latest CU. There are 54 mailboxes in the environment. All user mailboxes are connected to using either Outlook 2013 32-bit or Outlook 2016 32-bit , mostly
from Windows 10 machines of various build versions. There are still a handful of Windows 7 as well. All users have always used Outlook in Cached Exchange Mode since many years ago without experiencing this issue. Most users also use ActiveSync devices, mostly
iPhone and some Android.
I have a single user that had an issue about three weeks ago where he noticed new emails would show up on his iPhone but not in Outlook. If I turned off cached mode they would show up instantly. I went through extensive different possible solutions which I'll
list below. When none of them solved the issue I finally created a new Mailbox Database and moved his mailbox. It said there was one item corrupt item found:
A corrupted item was encountered: Folder property "Inbox" this is what I had hoped. I was hoping the issue was a corrupt item that would get left behind. The move succeeded and afterward Outlook began working correctly in cached mode again, on two
different computers.
Here's all the troubleshooting steps I had/have tried:
1. Disabled all Outlook Add-ins
2. Adjusted the Cache to only be for a few months instead of All.
3. Rebuilt his Outlook Profile (including OST)
4. Found that he has many, many, many folders and subfolders. Worked with him via archiving to PST and deleting older stuff to get it from 30GB mailbox with nearly 2,000 folders to a 10GB mailbox with 455 folders.
5. Tried setting up a profile on two other machines with different versions of Windows and Office, the issue followed.
6. Deleted old ActiveSync Devices from his OWA.
7. used MFCMapi to hard delete some subfolders from ExchangeSyncData which seemed to represent old Airsync devices.
This week, the issue started again. I'm really at a loss for what to do now. I've done some of the same testing from above and it seems to be the same issue all over again. Same user, not affecting anyone else. His mailbox is still on a separate database. I
really don't know what to do now short of creating yet another Database and moving him again. But, that only seemed to solve the issue for about a week last time.