If in Outlook you need to find the last modified date for a message  you can simply select it in the message list and press Alt+Enter

outlook last modified_01

To add the last modified date as a column in the message list you would;

  • Go to the View ribbon
  • Select Add column
  • Change the “Select available columns from” drop down to “Date/time fields”
  • Add modified to the right
  • Change the order as required
  • Press OK