From Homestar Runner Wiki
Server-side scripting is a web technology that allows a server to perform more advanced tasks. The most popular example of this technology is PHP, and is in fact the language that powers this wiki. When homestarrunner.com was hosted by Yahoo!, The Brothers Chaps were (presumably) limited to using the MivaScript scripting language, which is more commonly used for e-commerce websites. MivaScript was rarely used on the site when The Brothers Chaps were hosted by Yahoo!, but now MivaScript, or any server-side scripting technology for that matter, has not been used for 10 years. The last notable use of MivaScript was on the Message Bored, which closed in 2003. These files can be identified by the extension ".mv".
Yahoo! has since disallowed the execution of MivaScript files on their hosting service. As of mid-2009, instead of showing a notification that the script cannot run, the source code of the MivaScript file is revealed.
- Email Updates — Uses a script called "simplemail.mv" to add the given email address to a mailing list. Since the source is now revealed, it is shown that simplemail.mv was a MivaScript created by Yahoo!
- Strong Bad's Message Bored — In the Late Nite JengaJam Interview, Mike recalls that the board was powered by MivaScript.