Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Sun, 7 Dec 2025 01:12:26 -0600

The original message was received at Sun, 7 Dec 2025 01:12:25 -0600
from m0076161.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 [CO1PEPF000066EC.namprd05.prod.outlook.com 2025-12-07T07:12:26.486Z 08DE34023FEF8A85])

   ----- Transcript of session follows -----
... while talking to regalbeloit.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [CO1PEPF000066EC.namprd05.prod.outlook.com 2025-12-07T07:12:26.486Z 08DE34023FEF8A85]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [CO1PEPF000066EC.namprd05.prod.outlook.com 2025-12-07T07:12:26.486Z 08DE34023FEF8A85]