From Name = /0=First Organization/ou=Exchange Administrative Group...

Hi Danielle K

Outlook is displaying the LegacyExchangeDN (X.500) address instead of your normal email because it cannot properly resolve the sender identity after moving the message.

This typically happens when Outlook re-processes message properties (especially when moving items to a Personal folder/PST) and falls back to cached legacy values. This is generally a client-side resolution/display issue, not a mail delivery problem

In this context, you can try the following approaches to see if it help:

1. Create a new Outlook profile (most effective) Rebuild the entire Outlook cache and identity resolution:

• Control Panel > Mail > Show Profiles > Add
• Reconfigure your account and test again This removes any hidden corruption in address resolution.

2. Recreate the destination PST (if using Personal folders)

• Create a new Outlook Data File (.pst)
• Move a few emails into the new PST If the issue disappears, the original PST contains problematic metadata.

3. Validate it is only a display issue

• Send a test email externally and verify how the sender appears
• Check if replies work normally If recipients see the correct address, no mail flow issue exists and no server-side fix is required.

Hope my answer will help you.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".   

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.