I need to highlight an email addresses in text but not highlight them if contained in HTML tags, content, or attributes. For example, the string [email protected] must be converted to <a href="mailto:[email protected]">[email protected]</a> But email addresses in the string <a href="mailto:[email protected]">[email protected]</a> must not be processed. I've tried something like this regexp: (?<![":])[a-zA-Z0-9._%-+]+@[a-zA-Z0-9._%-]+.[a-zA-Z]{2,6}(?!") but it doesn't work properly.