YPOPs! is an open-source initiative to provide free POP3 access to your Yahoo! Mail account. It emulates a POP3 server and enables popular email clients like Outlook, Netscape, Eudora, Mozilla, etc. to download email from Yahoo! accounts. It provides a POP3 server interface at one end to talk to email clients and an HTTP client (browser) interface at the other which allows it to talk to Yahoo.
YPOPs! has the following other editions available: YPOPs! for Mac OS X and YPOPs! for Linux.