Bạn nên thực hiện một sự chuyển đổi thử nghiệm bằng cách sử dụng Migration Wizard trước khi thực hiện một sự chuyển đổi trực tiếp. Chuyển từ Microsoft Exchange Server và hệ thống thư khác | 10-4 Chapter 10 SMTP Protocol Configuration and Management 4. Host01 identifies Server01 as the recipient using the rcpt to command. Server01 returns response 250. 5. Host01 indicates that it is ready to send the message using the data command. Server01 returns a 354 response which indicates that the message should start. 6. Host01 sends the message. 7. Host01 indicates the end of the session using the quit command. Server01 returns a 221 response indicating that the SMTP service is closing the connection. Common SMTP Commands The SMTP commands define the mail transfer or the mail system function requested by the user. The commands consist of alphabetic character strings terminated by the carriage return line feed character CRLF . If a command code has parameters then it is followed by a space character SP the parameters and then CRLF . Table 10-1 lists the common SMTP commands. This list is not comprehensive. A full list of commands can be found in the RFCs. Table 10-1 Common SMTP Commands Command Description helo Requests an SMTP session and identifies the sending SMTP host to the receiving SMTP host. The argument field contains the fully qualified domain name FQDN of the sending host. mail from Identifies the sender of the message. This is not necessarily the same as the sending SMTP host for example the sending host could be acting as a relay. rcpt to Identifies the message recipient. If there are several recipients then the command is used for each recipient. data Indicates that the sending host is ready to transmit the message. quit Indicates the end of the SMTP session. rset Aborts the current mail transaction. quit Disconnects the TCP session. vrfy Allows the sending host to verify that the recipient is valid before sending the message. turn Triggers the recipient server to send queued messages destined for the sending server. This command is used in a dial-up environment to poll a host for queued messages. Lesson 1 Managing SMTP Message Transfer Support .
