Microsoft Defender for Office 365
Email and collaborationAnti Spam Bulk Complaint Level Bcl About
In brief
The page now explains that `X-MS-Exchange-Organization-BulkStamping` is used only during message transport and removed before delivery to the mailbox, so recipients cannot see it in message headers.
What Defender admins need to know
Administrators should not expect this header to appear in delivered messages. No action is required.
Summaries are generated from the documentation change itself.
Documentation change
View on Microsoft LearnThe comparison below shows only the changed extract. Use the full-page view for complete context.
- tier2
description: Admins can learn about bulk email detection, including the bulk complain level (BCL) values that are used in Microsoft 365.
ms.service: defender-office-365
ms.date: 2026-
08-25T00:10-15T00:00:00.0000000Z locale: en-us document_id: ca3bed41-6b2a-7917-f084-c920d4aaa0b6 document_version_independent_id: ca3bed41-6b2a-7917-f084-c920d4aaa0b6
For previous Preview customers, the rule that set X-MS-Exchange-Organization-BulkStamping to the value 1 to tag messages as Bulk is no longer required.
The X-MS-Exchange-Organization-BulkStamping header is an internal header that's used only during message transport. The header is removed before the message is delivered to the mailbox, so it isn't visible in the message headers that recipients see. This behavior is by design.
To enable bulk mail delivery to the Promotions folder, do the following steps:
Tip
@@ -18,7 +18,7 @@ ms.collection: - tier2 description: Admins can learn about bulk email detection, including the bulk complain level (BCL) values that are used in Microsoft 365. ms.service: defender-office-365-ms.date: 2026-08-25T00:00:00.0000000Z+ms.date: 2026-10-15T00:00:00.0000000Z locale: en-us document_id: ca3bed41-6b2a-7917-f084-c920d4aaa0b6 document_version_independent_id: ca3bed41-6b2a-7917-f084-c920d4aaa0b6@@ -134,6 +134,8 @@ To prevent mail *from specific senders* or *to specific recipients* from receivi
For previous Preview customers, the rule that set `X-MS-Exchange-Organization-BulkStamping` to the value `1` to tag messages as **Bulk** is no longer required.
+The `X-MS-Exchange-Organization-BulkStamping` header is an internal header that's used only during message transport. The header is removed before the message is delivered to the mailbox, so it isn't visible in the message headers that recipients see. This behavior is by design.
+
To enable bulk mail delivery to the **Promotions** folder, do the following steps:
Tip