Case sensitivity
Regular expression pattern matching in FortiMail is case insensitive. For example, bad language blocks bad language, Bad LAnguaGe, etc. Therefore, the regular expression /i, which may be used to make a word or phrase case insensitive in other products, should not be used in the FortiMail configuration.
However, prefixing a string with (?-i) can force off case insensitivity. For example, (?-i)abc will match string abc with case sensitivity; ABC or Abc won't match it.