Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Wed, 1 Oct 2025 16:58:05 -0400

The original message was received at Wed, 1 Oct 2025 16:58:03 -0400
from m0090834.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 [MWH0EPF000A6734.namprd04.prod.outlook.com 2025-10-01T20:58:05.285Z 08DE00B1AACB0C82])

   ----- Transcript of session follows -----
... while talking to lairdtech-com.mail.protection.outlook.com.:
>>> DATA
<<< 550 5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [MWH0EPF000A6734.namprd04.prod.outlook.com 2025-10-01T20:58:05.285Z 08DE00B1AACB0C82]
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need rcpt command [MWH0EPF000A6734.namprd04.prod.outlook.com 2025-10-01T20:58:05.285Z 08DE00B1AACB0C82]