Mimecast for Outlook - Incompatibility with New Outlook - Jun 2024

Service Update

Availability	Currently Available
Product(s)	End User Applications - Mimecast for Outlook
Who's affected	All Mimecast for Outlook users

Overview

We are aware of the recent launch of Microsoft's new Outlook on Windows client, allowing users to opt-in to a new version of Outlook, and its lack of compatibility with Mimecast for Outlook.

The new Outlook client does not support COM Add-Ins, including Mimecast for Outlook. Currently, there is no straightforward migration path to the Office Add-In framework supported by the new Outlook client. Limited programmatic functionality in the new Microsoft Outlook prevents us from delivering Mimecast for Outlook in its current form. Microsoft has also not provided a timeline for the general release of the new Outlook client, or, the end of support for the 'Classic' Outlook.

Recommended Actions 

If you are using the new Outlook preview, the following applies:

• Mimecast Essentials for Outlook and the Mimecast Personal Portal remain accessible for Mimecast features.
• Customers who wish to continue using Mimecast for Outlook must revert to the 'Classic' Outlook. We are actively assessing our End-User Application portfolio to best deliver Mimecast features.
• Mimecast for Outlook (MfO) will not function with the new Outlook due to the lack of COM add-in support.
• Mimecast Essentials for Outlook (MEO) will remain fully supported with the current feature set.
• Microsoft allows opt-in to the new Outlook with at least one year's notice before transitioning to an opt-out model, followed by another year's notice before making it the default experience. Administrators can manage user opt-in options as outlined in the Microsoft Admin Control Guide.
  • Click HERE (external link) for the Microsoft article on managing access to the new Outlook client.
  • Click HERE (external link) for the Microsoft article on their opt-in, opt-out development model of the new Outlook client.

Future Developments

We are currently gathering requirements to develop an alternative solution, potentially replacing the existing platform-dependent applications. This new solution will offer a unified and modernized user experience, serving as an alternative to the following applications:

• Mimecast for Mac
• Mimecast for Mobile
• Mimecast for Outlook
• Mimecast Personal Portal

We are dedicated to providing the best possible experience, we appreciate your understanding and patience and will keep you updated with further developments as more information becomes available.

See Also...

• The new Outlook for Windows for organization admins (external link)
• New Outlook for Windows: A Guide to Product Availability (external link)