Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Mon, 15 Sep 2025 06:13:08 GMT

The original message was received at Mon, 15 Sep 2025 06:13:08 GMT
from m0204702.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 [DB5PEPF00014B89.eurprd02.prod.outlook.com 2025-09-15T06:13:08.481Z 08DDED96B1EF3D67])

   ----- Transcript of session follows -----
... while talking to sweco-se.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [DB5PEPF00014B89.eurprd02.prod.outlook.com 2025-09-15T06:13:08.481Z 08DDED96B1EF3D67]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [DB5PEPF00014B89.eurprd02.prod.outlook.com 2025-09-15T06:13:08.481Z 08DDED96B1EF3D67]