Microsoft Defender for Office 365: Handling of promotional email - Action required before General availability

Updated July 7, 2026: We have updated the timeline. Thank you for your patience. 

[What and Why]

We're improving how promotional email is identified and managed in Microsoft Defender for Office 365. Messages identified as promotional will now be tagged as “Promotions” (previously tagged “Bulk” in private preview) and can be automatically routed to a dedicated Promotions folder.

These enhancements learn from user actions (such as moving messages in or out of the folder) to improve accuracy over time. This helps reduce inbox clutter while ensuring users still receive the promotional content they value—enhancing overall productivity and email hygiene.

This message is a follow-up to MC1279093, which introduced this feature during preview.

[Rollout Schedule]

• General Availability (Worldwide): Rollout begins in late July 2026 (previously early July) and is expected to complete by late August 2026 (previously late July).

[Impact on your organization]

Who is affected:

• All Admins and Exchange Online users who participated in Microsoft Defender for Office 365 preview program. 

Platforms/Services:

• Exchange Online
• Outlook (Web, Desktop, Mobile)
• Microsoft Defender for Office 365

What will happen:

At General Availability:

• Promotional messages will be automatically tagged as “Promotions” (replacing the “Bulk” label used in preview).
• By default, all incoming messages are evaluated for promotional content—no opt-in required.
• When Bulk Moves Enabled is configured, messages will move automatically to a Promotions folder created in user mailboxes.
• The system will learn from user behavior (moving messages in/out of the Promotions folder) and apply that learning to future messages.
• Users can create inbox rules referencing the Promotions tag.
• The previous dependency on the X-MS-Exchange-Organization-BulkStamping header for classification is no longer required.
• Admins can exclude the default tagging and movement for specific sender address by explicitly creating a new rule and setting the header value to 0 via mail flow rules.

[Action Required / Recommendations]

Recommended actions:

• By the end of July 2026, Create a new Exchange transport rule to exclude specific sender addresses from Promotions stamping (refer to Step 1).
  • This new rule should have a higher priority than the existing preview rule.
  • Configure the rule to set X-MS-Exchange-Organization-BulkStamping to 0.
• Ensure the new rule aligns with the default behavior and remove unnecessary dependencies on header stamping BulkStamping = 1 which was required for opt-in preview.
• By end of August 2026, delete the existing preview rule that is no longer needed after rollout completes (refer to Step 2).
• Inform helpdesk staff and impacted admins about the new Promotions folder experience and any sender exclusions you maintain.

Step 1: Create a new Exchange transport rule to exclude sender addresses from Promotions stamping:

1. In the Exchange admin center, open the Rules page.
2. Select Add a rule > Create a new rule.
3. On the Set rule conditions page:
• Name: Enter a descriptive name, such as promotional mail exclusion.
• Apply this rule if: Select The sender > is this person.
• Copy the sender addresses from the existing preview rule, and then select Save.
• Select Modify the message properties.
• Set the message header to X-MS-Exchange-Organization-BulkStamping.
• Set the header value to 0.
4. In Rule settings, ensure Stop processing more rules remains unchecked.
5. Select Next and finish creating the rule.
6. On the Rules page, ensure the rule is:
• Enabled
• At the top of the list (Priority 0)

Step 2: By end of August 2026, delete the existing preview rule

1. Go to the Rules page in the Exchange admin center.
2. Locate the existing preview rule.
3. Select Delete.
4. Confirm deletion.

Learn more: Mail flow rules (transport rules) in Exchange Online | Microsoft Learn

[Compliance considerations]

Consideration	Impact
Does the change alter how existing customer data is processed, stored, or accessed?	Email messages are analyzed using updated classification logic to determine promotional content, replacing reliance on transport headers.
Does the change introduce or significantly modify AI/ML capabilities that interact with customer data?	The system classify promotional messages and adapt based on user actions such as moving messages between folders.
Does the change include an admin control and can it be controlled through Entra ID group membership?	Admins can control behavior using Exchange mail flow rules (for example, setting the BulkStamping header to 0 to opt out). Group-based targeting may be applied through rule conditions.
Does the change allow a user to enable or disable the feature themselves?	Users indirectly influence behavior by moving messages in or out of the Promotions folder, which trains the system for future classification.
Does the change modify how users can access or organize their data?	A new Promotions folder may automatically organize messages, which may change how users access and manage promotional email compared to their previous inbox experience.
Does the change alter how admins can monitor or demonstrate compliance activities?	While no direct change to compliance tooling is introduced, changes to message classification and routing could affect how email data appears in investigations or reporting scenarios.