Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Tue, 30 Sep 2025 13:00:41 +0200

The original message was received at Tue, 30 Sep 2025 13:00:40 +0200
from m0275159.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 [DU6PEPF0000A7DF.eurprd02.prod.outlook.com 2025-09-30T11:00:41.089Z 08DDFAC15919C895])

   ----- Transcript of session follows -----
... while talking to eka-com.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [DU6PEPF0000A7DF.eurprd02.prod.outlook.com 2025-09-30T11:00:41.089Z 08DDFAC15919C895]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [DU6PEPF0000A7DF.eurprd02.prod.outlook.com 2025-09-30T11:00:41.089Z 08DDFAC15919C895]