Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 11 Sep 2025 08:37:05 +0200

The original message was received at Thu, 11 Sep 2025 08:37:04 +0200
from m0220688.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 [DB5PEPF00014B99.eurprd02.prod.outlook.com 2025-09-11T06:37:05.414Z 08DDF08F572E90E3])

   ----- Transcript of session follows -----
... while talking to storebrand.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [DB5PEPF00014B99.eurprd02.prod.outlook.com 2025-09-11T06:37:05.414Z 08DDF08F572E90E3]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [DB5PEPF00014B99.eurprd02.prod.outlook.com 2025-09-11T06:37:05.414Z 08DDF08F572E90E3]