Subject Regular Expressions Syntax

The Subject Regular Expression field allows you to enter values in the Python Regular Expressions (RE) syntax.

For example, to create a DLP policy rule to find emails that contains the string [secure] in the email subject, add (?i)\[secure] or \[secure] where (?i) is used to specify that it is case insensitive to the Subject Regular Expression field in the policy.

To create a DLP policy rule to find emails that contain either the exact strings [secure] or [encrypt] in the email subject, you can add either \[secure\]|\[encrypt\] or ex \[secure]|\[encrypt] to the Subject Regular Expression field in the policy.

For more information, see Python regular expressions documentation.

The symbols for the start (^) and end ($) of a line are not supported. See Unsupported Regex Patterns in DLP.

To create a DLP policy rule that detects emails containing the exact word sec in the email body (but not words like Security or Seconds), regardless of whether it's at the beginning of a sentence or separated by spaces or tabs, you can use the boundary marker \b. For example, use \bsec\b.

Unsupported Regex Patterns in DLP

When creating a DLP rule using regular expressions (regex), the following patterns are not supported.

• Regular expressions with a length shorter than three characters are not supported.

• The system also blocks the following regex patterns, as they may cause inefficient or inaccurate matching:

  [
  ".",
  ".*",
  ".+",
  ".?",
  ".{0,}",
  ".*?",
  ".+?",
  "[\s\S]",
  "[\s\S]+",
  "[\w\W]",
  "[\w\W]+",
  "\s*",
  "\S*",
  "\w*",
  "\W*",
  "\d*",
  "\D*",
  "\s+",
  "\S+",
  "\w+",
  "\W+",
  "\d+",
  "\D+",
  ]