Implementing Policy › Email Administration › Mailbox Rules › Special Characters in Regular Expressions

Special Characters in Regular Expressions

Pattern matching for the filters in mailbox rules follows the rules for ASCII Regular Expressions with C-style special characters.

Important! We recommend that you are familiar with Regex syntax to use special characters in regular expressions.

For example, consider the following special characters for Regex patterns that apply to regular expressions in mailbox rules:

\t

Specifies a horizontal tab. In filter strings for mailbox rules, \t matches the beginning and end of text (and tabs), and is specific to the Mail Eater.

\r

Specifies a carriage return (return to the beginning of the current line).

Note: Do not use \r for searching message subjects or sender addresses.

\n

Specifies a newline (combination of line feed and carriage return).

Note: Do not use \n for searching message subjects or sender addresses.

\t, \r, and \n are the special characters that occur most often in regular expressions for mailbox rules.

Example: \t, \r, and \n Use

[ \t]request[ \t]

Searches text for the word request. The brackets match any one character from the set, including the space, so [ \t] matches a space or a tab.

[\r\n]+critical[ \t\r\n]

Searches text for the word critical at the start of a line, the start of the message, or as the entire contents of a line. The brackets match any one character from the set, and the + (plus sign) matches one or more of the previous, so [\r\n]+ matches one or more carriage returns and newlines.