I recently switched from Entourage 2007 to Outlook 2011, on El Capitan.

Many emails that were imported are not displaying the sent date in the Main Window. They contain the correct date in the email header when I open the email, but they have a blank in the "Date Received" column.

The common element is that they are all my sent emails, but not all of them. Just ones from a period from about 2006-present.

If I export them to an .mbox format and reimport them, the current date and time shows up, even though the header shows the correct date in the past.

How can I get the date that is in the message (in the header) to display as the "date Received"?