Email Security - API - Graymail Control Enhancements - Jun 2026

Service Update

Availability	June 23rd, 2026
Product(s)	Email Security - API
Who's affected	Administrators and End Users

Overview

Mimecast is pleased to announce two enhancements to Graymail Control in Email Security - API. Administrators now have four distinct options for how Graymail messages are handled, offering full flexibility, from complete visibility-only monitoring to active Junk folder enforcement. In addition, when a message is moved to the Junk folder, end users can now trigger a self-service rescue by clicking ‘Not Junk’ in Outlook. Mimecast honors that signal automatically, preventing future disruption from the same sender without any Administrator intervention.

What's changing

Graymail Control: Expanded Policy Options: Previously, Graymail Control provided two options: Move to Junk and Apply Spam Policy Action. Now, Administrators have the flexibility to choose from four options:

Option	Behavior	Best For
Monitor	Graymail is logged and delivered to the inbox as normal. Administrators can view detection data without disrupting the user experience.	Migration periods and tuning a new policy with real data.
None	No action is taken. The message is delivered to the inbox unaffected. Detection is still logged, and full visibility is retained.	Organizations where Graymail is welcomed and interception is not required.
Move to Junk (Default)	The message is moved to the recipient's Outlook Junk folder. The user can click Not Junk to move it to the inbox. The sender is automatically added to Managed Senders, ensuring future messages are delivered directly.	Default configuration. Maximum control with self-service user rescue.
Apply Spam Policy Action	Graymail is handled using the same action configured for the Spam Protection policy.	Organizations that want Graymail and spam handled uniformly under a single policy action.

• End User "Not Junk" Signal: When Graymail Control is set to Move to Junk and a user marks a message as Not Junk in Outlook, Mimecast honors that signal. The following actions occur automatically:
  • The message moves from the Junk folder to the user's inbox.
  • The sender is automatically added to managed senders.
  • Future messages from that sender are delivered directly to the inbox. No repeat disruption occurs.
  • The feedback loop closes itself. Users self-rescue without raising support tickets, and the managed senders list grows organically from real user signals.

The Not Junk signal is only honored when Graymail Control is configured as Move to Junk. In Monitor, None, or Apply Spam Policy Action configurations, messages are not placed in the Junk folder and no end-user rescue action is available.

Recommended actions

Review your current Graymail Control setting in your Spam Protection policy:

1. Log in to the Mimecast Administration Console.
2. Navigate to Policies | Spam Protection Policies.
3. Edit your policy and locate the Graymail Control option under the Configuration section.
4. Select the option appropriate for your organization and click Save.

For most production deployments, Move to Junk (Default) combined with the end-user Not Junk signal provides the best balance of protection and self-service.

See Also...

• Email Security - API - Spam Protection Policy
• Email Security - API - Policies Overview