The conditions are PCRE regular expressions, applied to the message body or one of the headers. The condition works if it is possible to apply an expression to the specified part of a message. The checking is case-insensitive. If you don't want to study syntax of regular expressions, then enter expression as a text from letters, digits and spaces. The condition will be satisfied if the text from expression is a substring of the checked part of message.

Here are several examples of the expressions:

╖          "foo bar"
The expression is satisfied if the text contains a substring "foo bar".

╖          "foo\s+bar"
The same as above, but there may be one or more spaces between foo and bar.
"^foo"
The expression is satisfied if the text starts from "foo".

╖          "bar$"
The expression is satisfied if the text ends with "bar".

╖          "^foo bar$"
The expression is satisfied if the text equals to "foo bar".

 

You can read more about regular expressions in The Bat! manual.

The condition can be marked as Strong. In that case the rule will be satisfied if that condition is true, independently from other conditions of the rule.

The negation flag (Not operation) can be applied to a condition using the corresponding checkbox.