- due to the exceeding maximum number of open objects (folders) an Exchange server can allow within a session, all the users are processed under the same session, so all open folders for all users can add up.
Step 1: Migrating User With A PST File
To resolve the issue without having to change the folder structure, try migrating the user with a PST file. The number of open folders for a user depends on the number of child folders under a parent folder. For example, a folder tree with 10 children under a parent wouldn’t hit the limit, however 500 folders under a single folder would hit the limit.