Monitoring only outbound email

Symantec Data Loss Prevention
can capture inbound email and outbound email at an organization. Outbound email is often identified as the most important email to monitor. In most organizations, the email servers are located in a set of subnets.
  1. To set up SMTP to monitor only a certain set of subnets
  2. Select
    System > Settings > Protocols
    from the navigation bar.
  3. Select the SMTP protocol.
  4. In the
    Filtering (may override at server level)
    section of the page, enter the following in the
    Content
    field:
    +,*,10.1.0/16;-,*,*
    This example assumes that the source net where your Servers are located is 10.1.0.0 with a subnet mask of 255.255.0.0. The rule filters out any SMTP traffic not coming from the 10.1 subnet.
  5. Click
    Save
    , and then restart the monitors.
You must make the same change in local Server configurations.