This code detects the most common user agents (web browsers) and notifies you via email if it is not a recognized user agent as defined in the code. Usually this will be a bot of some sort. Extrememly useful for tracking how often Google, Yahoo, etc visits your site. It will email you the bot and a reverse IP lookup url with the IP appended so you can verify if it is a "good bot" or a "bad (spam) bot" (then you can block that IP or stop processing of the page). Use this in your home page or as an include file throughout your site. Nothing fancy it should work on MX also although I have not tested it there.