How Does Email DLP Work?
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Enterprise DLP

How Does Email DLP Work?

Table of Contents

How Does Email DLP Work?

Learn more about the Email DLP architecture and how emails are transported to and from
Enterprise Data Loss Prevention (E-DLP)
for inspection.
Where Can I Use This?
What Do I Need?
  • SaaS Security
  • Enterprise Data Loss Prevention (E-DLP)
    license
  • SaaS Security
    license
    Or
  • Any of the following licenses
    • Prisma Access
      CASB license
    • Next-Generation CASB for Prisma Access and NGFW (CASB-X)
      license
    • Data Security
      license
To prevent sensitive data exfiltration,
Enterprise Data Loss Prevention (E-DLP)
needs to perform inline inspection of all outbound emails. To do this, an inbound and outbound connectors are used to transport outbound emails to and from
Enterprise DLP
for inspection and verdict rendering. You must also create allow, block, and quarantine transport rules to specify the actions Microsoft Exchange or Gmail take based on the verdicts rendered by
Enterprise DLP
.
When
Enterprise DLP
inspects an email, an email header is added to indicate that
Enterprise DLP
has already inspected the email. If
Enterprise DLP
renders a
Block
or
Quarantine
verdict for inspected email, an email header to indicate the verdict is added as well. Emails that are already inspected are not transported to
Enterprise DLP
a second time and Microsoft Exchange or Gmail take action based on the existing email headers.
After
Enterprise DLP
inspects an email, it is returned back to Microsoft Exchange or Gmail for further action based on the rendered verdict.
The email flow for inline inspection of emails using
Enterprise DLP
is as follows:
  1. An email is sent from within your organization to a recipient outside your organization.
    The outbound email can be sent from a desktop mail client, a web-based mail client, or a mobile device.
  2. The email transport rule instructs Microsoft Exchange or Gmail to forward the outbound email to
    Enterprise DLP
    for inspection.
  3. Enterprise DLP
    inspects the email subject line, body, and attachments against your Email DLP policies and renders a verdict.
    Enterprise DLP
    adds email headers to mark that it's been inspected and what verdict was rendered.
    Enterprise DLP
    does not support inspection of document links contained in either the email subject or body.
  4. The email is returned back to Microsoft Exchange or Gmail.
  5. Microsoft Exchange or Gmail takes action based on their respective transport rules.
  6. Microsoft Exchange or Gmail send the allowed email to the intended recipient if allowed.
    An email is allowed if
    Enterprise DLP
    did not detect any sensitive data or if the email was quarantined and approved.

What Microsoft Exchange Online Licenses are Required for Email DLP?

Email DLP supports any Microsoft Exchange Online license, including Microsoft 365 Defender, Microsoft 365, and Office 365 E5 licenses for inline inspection of outbound emails using
Enterprise DLP
.
The type of Microsoft Exchange Online license you have activate determines the supported Email DLP functionality available to your Microsoft Exchange Online deployment.
The MSDN license is not supported for Email DLP. MSDN does not support the use of inbound connectors to route emails, which is required for
Enterprise DLP
to forward outbound emails back to Microsoft Exchange after inspection.

What Functionality Do Microsoft Exchange Licenses Support?

Email DLP supports the following functionality based on your active Microsoft Exchange license.
  • Any Microsoft Exchange Online licenses except MSDN
    • Inspect outbound emails
    • Block outbound emails containing sensitive data
    • Send outbound emails containing sensitive data for admin approval
    • Send outbound emails containing sensitive data for manager approval
  • Microsoft 365 Defender license
    See the Microsoft 365 Defender prerequisites for more information.
    • Inspect outbound emails
    • Block outbound emails containing sensitive data
    • Send outbound emails containing sensitive data for admin approval
    • Send outbound emails containing sensitive data for manager approval
    • Send outbound emails containing sensitive data to hosted quarantine for approval
  • Microsoft 365 or Office 365 E5 license
    • Inspect outbound emails
    • Block outbound emails containing sensitive data
    • Send outbound emails containing sensitive data for admin approval
    • Send outbound emails containing sensitive data for manager approval
    • Send outbound emails containing sensitive data to hosted quarantine for approval
    • Encrypt outbound emails containing sensitive data before they are sent to the recipient

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