CheckeredFlag used to be a modular web crawler. It never worked well, and was really more of an exercise than an actual working product. I've repurposed this project and now it's a super simple mail server and is ready for daily use. The intent for CheckeredFlag is to run on a developers workstation and provide a mail server running locally so the developer can work on applications needing a mail server without having to be connected to the internet. It provides basic SMTP support for sending email and POP3 support for receiving email. You might use CheckeredFlag when you're developing an email client or developing a web application that sends email.