Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Wed, 8 Oct 2025 11:31:56 GMT

The original message was received at Wed, 8 Oct 2025 11:31:56 GMT
from m0424592.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 [AM4PEPF00027A67.eurprd04.prod.outlook.com 2025-10-08T11:31:56.675Z 08DE0355A46874C6])

   ----- Transcript of session follows -----
... while talking to sgrailing-no.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [AM4PEPF00027A67.eurprd04.prod.outlook.com 2025-10-08T11:31:56.675Z 08DE0355A46874C6]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [AM4PEPF00027A67.eurprd04.prod.outlook.com 2025-10-08T11:31:56.675Z 08DE0355A46874C6]