Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Tue, 19 Aug 2025 09:32:29 GMT

The original message was received at Tue, 19 Aug 2025 09:32:28 GMT
from m0167566.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 [DB5PEPF00014B9D.eurprd02.prod.outlook.com 2025-08-19T09:32:29.071Z 08DDDC1D9CA4C2BA])

   ----- Transcript of session follows -----
... while talking to villeroyboch-se02b.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [DB5PEPF00014B9D.eurprd02.prod.outlook.com 2025-08-19T09:32:29.071Z 08DDDC1D9CA4C2BA]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [DB5PEPF00014B9D.eurprd02.prod.outlook.com 2025-08-19T09:32:29.071Z 08DDDC1D9CA4C2BA]