User Exchange mailboxes are "Over Limit".
The total size of attachments synced from the CRM to the email system caused the affected user's mailboxes to become full.
This issue can occur especially during the initial sync of CRM opportunities and/or cases to the email system, because it is common practice for CRM users to upload PDF and Office files to an opportunity or case in the CRM.
Solution for the Possible Cause
The solution assumes the following:
The overall solution has three main steps:
Requirement: Riva 188.8.131.5270 or higher. If unsure of the version that is installed, see Determine which version is installed.