Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Mon, 25 Aug 2025 08:18:21 +0200

The original message was received at Mon, 25 Aug 2025 08:18:20 +0200
from m0096059.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 [MR1PEPF00000D58.FRAP264.PROD.OUTLOOK.COM 2025-08-25T06:18:21.052Z 08DDE24191ADB7CC])

   ----- 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 [MR1PEPF00000D58.FRAP264.PROD.OUTLOOK.COM 2025-08-25T06:18:21.052Z 08DDE24191ADB7CC]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [MR1PEPF00000D58.FRAP264.PROD.OUTLOOK.COM 2025-08-25T06:18:21.052Z 08DDE24191ADB7CC]