[StAPF] Delivery Status Notification (Failure)

The following message to <hansjoerg.schmidttrenz(a)hk24.de&gt; was undeliverable. The reason for the problem: 5.1.0 - Unknown address error 550-'5.4.1 Recipient address rejected: Access denied. For more information see https://aka.ms/EXOSmtpErrors [DB1PEPF0003922F.eurprd03.prod.outlook.com 2025-07-06T10:58:48.827Z 08DDB90C974FC30C]'