Hi,

We weren't seeing this issue affect disk activity so much as it was affecting bandwidth usage. Outlook over IMAP would sometimes repeat Fetch commands hundreds of thousands of times, causing high bandwidth usage.

 

To see if your users experienced this issue you can check your IMAP bandwidth usage. Though a more reliable way to check is through your IMAP logs, assuming they're set to detailed. As high bandwidth usage can be caused by other sources, but masses of repeated FETCH commands in the logs should only be caused by this issue.