We're providing this update to keep you informed about our progress on delivering Mimecast functionality within Microsoft's New Outlook environment. As we approach the late 2025 timeframe for our intermediate solution, we want to ensure all customers understand where we are and what to expect in the coming months.
Since Our Last Update (Link)
The fundamental technical challenge remains unchanged: New Outlook does not support COM add-ins, which means Mimecast for Outlook cannot function with the new client. However, we want to emphasize that Mimecast Essentials for Outlook continues to work fully with New Outlook, providing core functionality:
- Report Messages
- Manage Senders
- Manage Held Messages
For other Mimecast End-User features, Mimecast Personal Portal remains the primary access point and provides complete functionality for all Mimecast features.
Progress Update on Our Roadmap
Intermediate Solution
We remain on track to deliver our intermediate solution. The updates include:
- New Outlook Add-in. We have released a new add-in designed to provide direct access to the Mimecast Personal Portal from within Outlook. This helps to reduce the friction of context-switching between applications and provide a more integrated user experience. More details: Mimecast Personal Portal - Outlook Add-in - Oct 2025
- Modernized Personal Portal. The Mimecast Personal Portal has had an interface redesign with modern UI/UX principles. This updated portal will serve as the foundation for accessing Mimecast features while we continue building toward our long-term unified platform. More Details: Mimecast Personal Portal - New UI - June 2025
- Improved User Experience. The combination of the new add-in and redesigned portal will significantly improve the day-to-day experience for users who have transitioned to New Outlook, making access to Archive Search, Continuity, Large File Send, Secure Messaging, and other features more seamless.
Long-Term Solution - 2026 and Beyond
Our vision for a unified, cross-platform web portal continues to progress on schedule:
Phase 1 (Early 2026):
- Complete platform framework and infrastructure
- Launch of the modernized web portal interface
- Full Archive Search functionality delivered
- Foundation established for subsequent feature rollouts
Subsequent Phases:
- Continuity features integrated into the unified platform
- Secure Messaging capabilities
- Large File Send functionality
- Gateway features including Hold Queue management, and Block lists
This phased approach ensures we deliver stable, high-quality functionality while building toward a comprehensive solution that consolidates all Mimecast end-user application features into a single, modern platform.
What Customers Should Be Doing Now
- Plan Your Transition Timeline - Review Microsoft's New Outlook rollout schedule for your organization and develop a migration plan that accounts for the current feature access methods.
- Configure CyberGraph Settings - If you use CyberGraph, ensure text-based warnings are configured at the organization level to maintain security notification visibility in New Outlook.
- Test with Pilot Groups - Before broad deployment of New Outlook, test the current workflow with a pilot group to identify pain points and develop user guidance specific to your organization.
- Familiarize Yourself with the Personal Portal - If you haven't already, take time to explore the Mimecast Personal Portal and understand how to access Archive Search, Large File Send, and other features you use regularly.
- Stay Informed - Follow Service Updates in the Knowledge Base to keep up to date with future updates.
Looking Ahead
We understand that the transition to New Outlook has created workflow changes for many of you. Our development teams are working diligently to deliver solutions that make accessing Mimecast functionality as seamless as possible while adapting to Microsoft's new architectural requirements.
The intermediate solution represents a step forward in improving the user experience. Following that, our 2026 unified platform will deliver a modern, comprehensive solution that works consistently across all devices.
Questions or Feedback?
If you have questions about New Outlook compatibility, need assistance configuring workarounds, or want to provide feedback on our roadmap, please:
- Contact Mimecast Support through your standard support channels
- Engage with our community forums for peer discussions
- Provide feedback through your Customer Success Manager
- Submit feature requests or concerns via the feedback mechanisms in your Mimecast Administration Console
Thank you for your continued partnership as we navigate this industry-wide transition together. Your feedback and patience as we develop these solutions is invaluable.
