PUBLIC MARKS with tag regexp

a PCRE that claim to be RFC822 compliant

Knowing how to use regular expressions is a lot like knowing how to cook: even though it is an incredibly useful skill, many people avoid learning. I‘ve been teaching people about regular expressions for years now, and since my voice is starting to give out I thought that I would write it down. This article covers steps one through five and a follow on article will get the rest.

Regular Expression Basic Syntax Reference