Email Reply Issue

Question

Hi All,

I'm experiencing different behavior between Outlook for Mac and Outlook for Windows when replying to emails from an external sender.

Scenario:

• An email is received from an external sender, for example: user1(at)extdomain1.com

Outlook for Mac:

• The sender is displayed as "Unverified."
• When I click Reply, the To field is empty and does not contain user1(at)extdomain1.com

Outlook for Windows:

• The email is not marked as "Unverified."
• However, when I click Reply, the recipient address is displayed as an encoded value instead of the original SMTP address, for example: user1<YUI?BI=8k6kl>; (The actual value contains a long encoded string rather than user1(at)extdomain1.com)

Has anyone encountered this issue before? Any guidance on what could cause this behavior would be appreciated. Is this something related DMARC/DKIM on sender domain, how can i verify sender DNS records and what records do i need to validate or verify

Answer 1

Hi Glenn Maxwell

Based on my research, I couldn't find any documented cases that match the exact behavior you're experiencing, where Outlook for Mac leaves the To field empty when replying while Outlook for Windows displays an encoded recipient address for the same message. 

To better understand your situation, could you please provide a few additional details? 

• Does this issue occur with all external senders, or only with messages from a specific domain?  
• Does the same behavior occur when replying in Outlook on the web (OWA)?  
• Could you share the Outlook version and build number on both your Mac and Windows devices?  
• If possible, could you also provide the message headers, particularly the From, Reply-To, Sender, and Authentication-Results headers? You can send the screenshot via private message to avoid exposing any personal or organizational information.   

Reference: View internet message headers in Outlook | Microsoft Support 

Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.   

I look forward to your update.  

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