IMAP4
full spelling ： Internet Message Access Protocol 4
IMAP4 (Internet Message Access Protocol 4) is an internet protocol allowing a local client to access email saved on a remote server. Earlier versions were defined by RFC 1730, while the updated IMAP4rev1 version is defined by RFC 2060. IMAP4 differs from POP in that clients can see the title and sender before deciding whether to receive a mail. IMAP4 is well-suited to mobile applications.