Use Case 7: DLP drop attachment

This use case is designed to block and notify the sender of an email with DLP X-Header response “DLP Drop Attachment” about the email’s unsuccessful delivery due to a sensitive attachment, along with an explanation message.

Steps

  1. In Microsoft Exchange admin center page, navigate to Mail flow > Rules. The Rules screen appears.
  2. Click Add a rule + > Create a new rule. The New transport rule screen appears.
  3. On the Set rule conditions page,
    1. Enter a unique name (ex. DLP Drop Attachment) for the rule in the Name field.
    2. In Apply this rule if* field:
      1. Select The message headers… from the first drop-down list.
      2. Then select matches any of these text patterns from the second drop-down list.
      3. Click Enter text. The specify header name window appears.
      4. Enter message header X-Forcepoint-DLP-Email and then click Save.
      5. Click Enter words. The specify words or phrases window appears.
      6. Enter header text DLP-Drop-Attachment and then click Save.
    3. In Do the following* field:
      1. Select Block the message from the first drop-down list.
      2. Then select reject the message and include an explanation from the second drop-down list.
      3. In specify rejection reason prompt, enter the alert message (ex. Your email was blocked due to a sensitive attachment. Please remove the attachment and resend the email to comply with your organization's DLP policy).
      4. Click Save.


    4. When you complete setting the Set rule conditions page, click Next.
  4. On the Set rule settings page, configure the following settings:
    1. Select Enforced as Rule mode.
    2. Select High in Severity.
    3. Tick Stop processing more rules.
    4. When you complete setting the Set rule settings page, click Next.
  5. On the Review and finish page, verify the settings and click Finish.
  6. The Transport rule created successfully message appears. Then, click Done.

    The inbound mail flow rule for the DLP drop attachment is created.

    Note: After creation of the mail flow rule (DLP drop attachment), it might take 30 minutes or more for the new rule to be applied to emails.