Mail Send (i)

There are many kinds of mail servers, first we understand the protocol used in the mail transfer process. SMTP

The SMTP (simple Mail Transfer Protocol) is simply a transport protocol, which is a set of rules for sending messages from source to destination to control how the letters are transferred. The SMTP protocol belongs to the TCP/IP protocol cluster, which helps each computer find the next destination when sending or relaying letters. The server specified by the SMTP protocol, you can send e-mail to the recipient's server, the whole process only a few minutes. The SMTP server is the outgoing mail server that follows the SMTP protocol and is used to send or relay outgoing e-mail messages. POP3

POP3, the full name is Post Office Protocol-version 3, the Post Office Protocol version 3. is a member of the TCP/IP protocol cluster, defined by RFC1939. This protocol is primarily used to support the use of client remote management of e-mail messages on the server. The POP3 protocol, which provides SSL encryption, is called Pop3s.

The POP protocol supports "offline" mail processing. The process is that the message is sent to the server, and the e-mail client invokes the mail client program to connect to the server and download all unread e-mail messages. This off-line access mode is a storage and forwarding service that delivers mail from the mail server to a personal terminal machine, typically a PC or MAC. Once the message is sent to the PC or Mac, the message on the mail server will be deleted. However, the current POP3 mail server can be "only download mail, server-side does not delete", that is, the improved POP3 protocol.

The use of the protocol during the transfer process is shown in the figure

Send mail from this computer to a local server or to a cross server using SMTP mail, the POP3 protocol is used by the mailbox user to receive mail from the server to which the mailbox is registered.

How the mailbox server is positioned.

@ The second half is actually an IP address