Hands down the best script of them all!
KMB uses the IMAP PHP functions making it both slim and fast.
KMB has runtime mail check, i.e. every time the script run on the webpage it check the mail inbox. This of course makes it very easy in that it doesn�t require cron jobs or scheduled tasks and in also makes post updates instantaneous, but it could at the same time mean lots of unnecessary mail server requests on a popular site.