Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi Johannes,
A Microsoft 365 E3 license includes Microsoft Purview Message Encryption, so an additional license is generally not required to use email encryption in either Classic Outlook or New Outlook.
First, please contact your IT administrator to confirm that Message Encryption has been configured and enabled for your organization. For more information, please consult: Set up Message Encryption
You should also refer this document Resolve Microsoft Purview Message Encryption issues - Microsoft 365 | Microsoft Learn to your IT admin and ask them to follow the article's troubleshooting steps. Please note that these steps must be performed by a Global Administrator and cannot be carried out by the end user.
For the missing email in Classic Outlook, please ask your IT administrator to run a message trace to determine whether the email was received by your organization's mail system and identify its delivery status.
In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support
If you have any questions or need further assistance, please feel free to share them in the comments on this post.
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