Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 26 Jun 2025 08:02:20 GMT

The original message was received at Thu, 26 Jun 2025 08:02:19 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 [AM3PEPF0000A799.eurprd04.prod.outlook.com 2025-06-26T08:02:19.640Z 08DDB43D43178D9E])

   ----- 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 [AM3PEPF0000A799.eurprd04.prod.outlook.com 2025-06-26T08:02:19.640Z 08DDB43D43178D9E]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [AM3PEPF0000A799.eurprd04.prod.outlook.com 2025-06-26T08:02:19.641Z 08DDB43D43178D9E]