Blue HttpMail is a library that connects to HTTPMail servers (such as hotmail.com) and a proxy that allows POP3, IMAP and SMTP access to those servers. Blue HttpMail is being developed using the open source library Blue http://bluelib.sourceforge.net
tuproxy is a RFC1939-compliant POP3 proxy server.
It is developed to fill the gap of a freely available POP3 proxy for Windows, but it is easily ported to other systems.
FiPPS is a simple POP3 proxy server for Windows which scans mail headers with regular expressions for spam/mailworms and deletes the mails without downloading them.
A mailgate-server, acting as a gateway between private networks of a company and Internet. The working scheme is simple: (internal mailbox)<-->(external Internet mailboxes). Uses POP3 protocol. Its work is gonna be completely transparent to the end users.
WinNT HTTPMail->POP3 service. HotPOP3 is a Windows NT service, written in C++, which acts as a proxy between an HTTPMail server (MSN Hotmail) and any POP3 email client.