StuffIt Expander: When some files are delivered via email, they're encoded in a standard Internet format known as 'MIME.' Most email programs support this standard, and will transparently decode the 'MIME' file for you. A few email programs, and any web-based email systems (like Yahoo Mail, Juno.com, and others) have trouble with the MIME files. StuffIt Expander can decode these files for you when your email program can't. It's available for free in both Macintosh and Windows versions.