Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Tue, 11 Nov 2025 09:04:05 GMT

The original message was received at Tue, 11 Nov 2025 09:04:05 GMT
from m0223513.ppops.net [127.0.0.1]

   ----- The following addresses had permanent fatal errors -----
<[email-masked]>
    (reason: 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [AMS0EPF000001A4.eurprd05.prod.outlook.com 2025-11-11T09:04:05.608Z 08DE203858B6B813])

   ----- Transcript of session follows -----
... while talking to nibe-com.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [AMS0EPF000001A4.eurprd05.prod.outlook.com 2025-11-11T09:04:05.608Z 08DE203858B6B813]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [AMS0EPF000001A4.eurprd05.prod.outlook.com 2025-11-11T09:04:05.608Z 08DE203858B6B813]