Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 16 Oct 2025 12:09:45 +0200

The original message was received at Thu, 16 Oct 2025 12:09:44 +0200
from m0096058.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 [PA2PEPF00019231.FRAP264.PROD.OUTLOOK.COM 2025-10-16T10:09:44.970Z 08DE0813F2C37978])

   ----- Transcript of session follows -----
... while talking to tarkett-com.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [PA2PEPF00019231.FRAP264.PROD.OUTLOOK.COM 2025-10-16T10:09:44.970Z 08DE0813F2C37978]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [PA2PEPF00019231.FRAP264.PROD.OUTLOOK.COM 2025-10-16T10:09:44.970Z 08DE0813F2C37978]