[Email DLP] Operation Test (Microsoft 365)

Target

• Customers who have completed the connection between Email DLP and Microsoft 365

Purpose

• To confirm that the connection between Email DLP and Microsoft 365 has been completed correctly, and that the filters are working as required.

Notes

1. The content of this article is based on the product as of January 2026 and is subject to change without notice.
2. Emails with simple subjects or empty/very short bodies may be flagged as suspicious by the recipient's content filter.
3. Due to updates or specification changes, some displays may differ.
4. Admin privileges for Email DLP are required to view the actual screens or perform configuration operations.
5. For instructions on how to access the administration, please refer to the following article.
   [Email DLP] How to log in to the Administration

Procedure

Preparation

1. Send a test email from Microsoft 365 to both internal and external recipients.
   * If necessary, please use the following template.

   • Subject

     Email DLP Connection Test (1st email)

   • Body

     The connection with Email DLP has been confirmed, so this is a test email.
     This is to confirm the filter processing.

Microsoft 365 Confirmation Procedure

1. Access the [Microsoft 365 admin center].

2. From the left menu, select [Exchange].

3. When the Exchange admin center is displayed, select [Mail flow] - [Message trace] from the left menu.

4. Select [+ Start a trace].

5. Enter the address that sent the test email in [Sender] and select [Search].
   If necessary, enter other filter conditions.

6. From the search results, select the test email sent to internal recipients.

7. In the [Status] column, confirm that it has not been forwarded to Email DLP.
   Confirm that [Connector name: ‎HENNGE Email DLP‎] is not displayed.

8. Return to the search screen and select the test email sent to external recipients from the search results.

9. In the [Status] column, confirm that it has been forwarded to Email DLP.
   Confirm that [Connector name: ‎HENNGE Email DLP‎] is displayed.
   Once you have confirmed the above, proceed to "Email DLP Confirmation Procedure".

   * If it has not been forwarded to Email DLP, please refer to the following page to check if there are any mistakes in the connection procedure.
   Email DLP Connection Procedure (Microsoft 365)

Email DLP Confirmation Procedure

1. Access the Email DLP administration, and from the left menu, go to [History] - [History].
   For instructions on how to access the administration, please refer to the following article.
   How to access the Email DLP Admin Console

   

2. Use the search box at the top right to search by any date, and confirm that only the test email sent to external recipients is displayed, and that emails sent to internal recipients are not displayed.
   For more details on search period and filter conditions, please refer to the following article as needed.
   [Email DLP] Search Filter History
    

   

3. Open the details of the test email sent to external recipients and confirm that the intended filters, actions, and rules have been applied.
   Depending on your requirements, please check by changing the conditions, such as with or without attachments.

   

Confirm DKIM Settings

1. Check the test email received on the recipient side and confirm from the header that DKIM verification has succeeded.
   * Please confirm that the DKIM item is "pass" using the Google Admin Toolbox Messageheader (external link).
   If DKIM is in test mode, it will display as pass(test mode).
   * For instructions on how to obtain the email header, refer to the "Procedure to check the header of received emails in Gmail" section in the following article.
   How to obtain the message source
2. Once DKIM verification is successful, remove "t=y;" from the TXT record added to the DNS server in [Email DLP] General Settings - DKIM Settings.
   * When editing, make sure there are no line breaks or extra spaces in the TXT record.