Service Update
| Availability | June 4th, 2025 |
| Product(s) | Mimecast Essentials for Outlook (MEO) |
| Who's affected | Mimecast Essentials for Outlook (MEO) users |
Overview
Mimecast is pleased to announce support for Nested Application Authentication for Mimecast Essentials for Outlook.
What's changing?
Customers who use Exchange Online can now enable Nested Application Authentication for Mimecast Essentials for Outlook. This serves as a replacement for the Exchange Identity Token-based authentication option, as Exchange Identity Tokens have been deprecated by Microsoft for Exchange Online.
Enabling Nested Application Authentication allows a user’s identity to be verified via Microsoft 365, reducing the need for users to manually authenticate.
Recommended actions
Customers using Exchange Online should review the Nested Application Authentication section of the Mimecast Essential for Outlook - Configuration article.
Comments
Thank you for the Service Update. When is the deadline to review the Nested Application Authentication?
We are having issues with the NAA authentication. We are on v1.3.16 on the MEO app.
NAA connector has been configured integrations, JWT auth is enabled in the authentication profile… Is there anything I'm missing here?
hi Dakota Hourie,
Many thanks for leaving this feedback with us.
Please take a look at the updated referenced article https://mimecastsupport.zendesk.com/hc/en-us/articles/34000732328979-Mimecast-Essentials-for-Outlook-Configuration and see if it answers your question.
Hi Paul,
Thank you for your comment.
In June 2025, legacy tokens will be turned off and you won't be able to turn them back on. In October 2025, it won't be possible to turn on legacy tokens, and they'll be disabled for all tenants.
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