Remove corrupt ActiveSync device from Exchange

當有 moblie device join exchange 時

• Hidden folders in the user mailbox
• AD as child items to the user account

How to fix

1. OWA

deletes the corrupted ActiveSync device that is visible from OWA

2. MFCMapi

Expand the "ExchangeSyncData"
Locate the corrupt device (a folder under ExchangeSyncData) and right click > Delete Folder
[I recommend a hard delete]

Delete Folder

Only delete a folder via MFCMAPI when you are really sure that you

do no longer want the folder and deleting via Outlook is not possible.