Totals in reports on mailbox content do not match what I can see in Outlook

Question:

I am trying to obtain a reliable report showing how many items users in our Exchange organization store in the Sent Items folder of their mailboxes. However,  Promodag Reports finds more items than I can see in Outlook. How come?

Answer:

Cached Exchange Mode is likely to be turned on in Outlook. As a consequence, the values you can see in Outlook reflect the current content of your *.ost file, while those shown in the report are directly retrieved from Exchange.

Our advice would be to directly connect to the mailbox through OWA. You would see the same number in the Sent Items folder than in Promodag Reports.

Related article: Why do content reports return fewer items than PowerShell?