|POP 3 RFC1939||POP 4 Specification||POP 4 FAQ||O3 mail system. Implementation of POP 4|
|10/17/2013 - UPDATE
There are now two known POP4 server implementations! As of 10/17/2013, the POP4.org domain and website are now hosted by simbey.com, which also runs the other POP4 server implementation. You can find out more information about the SimbeyServer and its implementation of the POP4 protocol and extensions here.