Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Tue, 30 Sep 2025 11:00:29 GMT

The original message was received at Tue, 30 Sep 2025 11:00:26 GMT
from m0167567.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 [AM3PEPF0000A795.eurprd04.prod.outlook.com 2025-09-30T11:00:29.056Z 08DDFBA82DC3C875])

   ----- Transcript of session follows -----
... while talking to villeroyboch-se02b.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [AM3PEPF0000A795.eurprd04.prod.outlook.com 2025-09-30T11:00:29.056Z 08DDFBA82DC3C875]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [AM3PEPF0000A795.eurprd04.prod.outlook.com 2025-09-30T11:00:29.056Z 08DDFBA82DC3C875]