【正文】 外文資料原文SMTP Service Extension for AuthenticationRFC 2554This document specifies an Internet standards track protocol for the Internet munity, and requests discussion and suggestions for improvements. Please refer to the current edition of the Internet Official Protocol Standards (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.There are usually two operating modes: SMTP to send and receive SMTP. Specific way: to send SMTP mail in the received user request to determine whether this local mail, if sent to the user39。s mailbox direct investment, or to check the remote mail server dns MX record, and the establishment of the remote received a twoway between the SMTP transmission channel, then by the sending SMTP mand issued by the receiving SMTP to receive, and answer the counterside delivery. Once the transmission channel is established, SMTP MAIL mand specifying the sender sends the message sender. If the recipient can receive mail SMTP OK response is returned. SMTP RCPT mand issued for the sender to confirm whether the message is received. If the SMTP recipient receives, it returns OK response。 if you cannot receive, then refused to accept response to issue (but does not suspend operation of the entire message), the two sides will repeat so many times. When the recipients receive all messages will receive a special sequence, if the recipient of the message successfully processed, it returns OK response.SMTP mands define the mail transfer or by userdefined system functions. Its mand is CRLF End of the string. In the case with parameters, the mand itself is SP and the parameters separately, if not directly, and with parameters CRLF Connection. Mailbox syntax and receiving sites must be consistent with the form. SMTP mands and responses are discussed below. Send operations involving different data objects, their mutual connection by different parameters. Reply Path parameter is the MAIL mand, the forward path is the RCPT mand parameter, the message date is the DATA mand. These arguments or data objects must follow the mand. This model also requires a different buffer to store the objects, that is, there is a path back buffer, a forward path buffer, the contents of a message buffer. The mand generates its own specific buffer, or to one or more of the contents of the buffer is cleared.An important feature of SMTP is its ability to transmit messages in the Relay, Transfer Service provides interprocess munication (IPCE), and this environment may include a network, several networks or a network subnet. Understand that the transmission system (or IPCE) is not a one to one very important. Process and other processes may be directly through the munications of known IPCE. Mail is an application or interprocess munication. Mail can be connected in different IPCE the process of internetwork mail delivery. More specifically, mail can be a host of different network relay transmission.Known as the Simple Mail Transfer Protocol SMTP (Simple Mail Transfer Protocol), aim to provide efficient and reliable message transfer. An important feature of SMTP is its ability to transmit messages in the Relay, that the message can be different relay hosts on the network transmission. Work in two situations: First, transmission from the client to the server。 second is from one server to another server. SMTP is a request / response protocol, it listen port 25, for receiving the user39。s Mail request to establish with the remote Mail server SMTP connection.Copyright NoticeCopyright (C) the Internet Society (1999). All Rights Reserved.1. IntroductionThis document defines an SMTP service extension [ESMTP] whereby an SMTP client may indicate an authentication mechanism to the server。 perform an authentication protocol exchange, and optionally negotiate security layer for subsequent protocol interactions. This extension is a profile of the Simple Authentication and Security Layer [SASL].2. Conventions Used in this DocumentIn examples, C: and S: indicate lines sent by the client and server respectively. The key words MUST, MUST NOT, SHOULD, SHOULD NOT, and MAY in this document are to be interpreted as defined in Key words for use in RFCs to Indicate Requirement Levels [KEYWORDS].3. The Authentication service extension(1) The name of the SMTP service extension is Authentication(2) The EHLO keyword value associated with this extension is AUTH(3) The AUTH EHLO keyword contains as a parameter a space separated list of the names of supported SASL mechanisms.(4) A new SMTP verb AUTH is defined(5) An optional parameter using the keyword AUTH is added to the MAIL FROM mand, and extends the maximum line length of the MAIL FROM mand by 500 characters.(6)