In computing, the Post Office Protocol (POP) is an application-layer Internet standard protocol which is being mainly used by limited e-mail clients to get back e-mail from a distant server over a TCP/IP connection. POP as well as IMAP (Internet Message Access Protocol) is the two mainly common Internet standard protocols for e-mail recovery. Virtually all current e-mail clients as well as servers support both. The POP protocol has been developed throughout numerous versions, with version 3 (POP3) being the existing standard.