Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 15 Jan 2026 13:11:34 +0200

The original message was received at Thu, 15 Jan 2026 13:11:20 +0200
from sink.edelkey.net [213.138.147.137]

   ----- 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 [DB1PEPF00039233.eurprd03.prod.outlook.com 2026-01-15T11:11:34.007Z 08DE53F47F2A1EF1])

   ----- Transcript of session follows -----
... while talking to halton-com.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [DB1PEPF00039233.eurprd03.prod.outlook.com 2026-01-15T11:11:34.007Z 08DE53F47F2A1EF1]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [DB1PEPF00039233.eurprd03.prod.outlook.com 2026-01-15T11:11:34.007Z 08DE53F47F2A1EF1]