Hi @Al ,
Were the messages sent/received within your organization?
If so, for the messages from internal users in your Exchange server, it would show the display name instead of email address in From field, which is by design and we couldn't change it. Here are some relevant threads, for your reference :
- How to show email address not just name in From and To fields
- Outlook 2013 : How to show Sender's email address in Inbox for Internal Users (Office 365)
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.