FreePOPs  is a POP3 daemon plus a LUA  interpreter and some extra libraries for HTTP and HTML parsing. Its main purpose is translating local POP3 requests to remote HTTP actions on the supported web-mails, but it is really more flexible. For example there is a plugin to read news from a website as if they were mails in a mailbox. You can easily extend FreePOPs on the fly, without even restarting it. FreePOPs 0.0.14 also offers a Gmail  plugin.