rfc2197.txt

用C#开发实现SMTP相关技术,能接收到带附件的邮件服务功能.

RFC 2197                 SMTP Service Extension           September 1997


    (5)   MUST NOT buffer responses to EHLO, DATA, VRFY, EXPN,
          TURN, QUIT, and NOOP.

    (6)   MUST NOT buffer responses to unrecognized commands.

    (7)   MUST send all pending responses immediately whenever
          the local TCP input buffer is emptied.

    (8)   MUST NOT make assumptions about commands that are yet
          to be received.

    (9)   SHOULD issue response text that indicates, either
          implicitly or explicitly, what command the response
          matches.

   The overriding intent of these server requirements is to make it as
   easy as possible for servers to conform to these pipelining
   extensions.

5.  Examples

   Consider the following SMTP dialogue that does not use pipelining:

   S: <wait for open connection>
   C: <open connection to server>
   S: 220 innosoft.com SMTP service ready
   C: HELO dbc.mtview.ca.us
   S: 250 innosoft.com
   C: MAIL FROM:<[e-mail]>
   S: 250 sender <[e-mail]> OK
   C: RCPT TO:<[e-mail]>
   S: 250 recipient <[e-mail]> OK
   C: RCPT TO:<[e-mail]>
   S: 250 recipient <[e-mail]> OK
   C: RCPT TO:<[e-mail]>
   S: 250 recipient <[e-mail]> OK
   C: DATA
   S: 354 enter mail, end with line containing only "."
    ...
   C: .
   S: 250 message sent
   C: QUIT
   S: 221 goodbye








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RFC 2197                 SMTP Service Extension           September 1997


   The client waits for a server response a total of 9 times in this
   simple example. But if pipelining is employed the following dialogue
   is possible:

   S: <wait for open connection>
   C: <open connection to server>
   S: 220 innosoft.com SMTP service ready
   C: EHLO dbc.mtview.ca.us
   S: 250-innosoft.com
   S: 250 PIPELINING
   C: MAIL FROM:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: DATA
   S: 250 sender <[e-mail]> OK
   S: 250 recipient <[e-mail]> OK
   S: 250 recipient <[e-mail]> OK
   S: 250 recipient <[e-mail]> OK
   S: 354 enter mail, end with line containing only "."
    ...
   C: .
   C: QUIT
   S: 250 message sent
   S: 221 goodbye


   The total number of turnarounds has been reduced from 9 to 4.

   The next example illustrates one possible form of behavior when
   pipelining is used and all recipients are rejected:

   S: <wait for open connection>
   C: <open connection to server>
   S: 220 innosoft.com SMTP service ready
   C: EHLO dbc.mtview.ca.us
   S: 250-innosoft.com
   S: 250 PIPELINING
   C: MAIL FROM:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: DATA
   S: 250 sender <[e-mail]> OK
   S: 550 remote mail to <[e-mail]> not allowed
   S: 550 remote mail to <[e-mail]> not allowed
   S: 554 no valid recipients given
   C: QUIT
   S: 221 goodbye



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RFC 2197                 SMTP Service Extension           September 1997


   The client SMTP waits for the server 4 times here as well. If the
   server SMTP does not check for at least one valid recipient prior to
   accepting the DATA command, the following dialogue would result:

   S: <wait for open connection>
   C: <open connection to server>
   S: 220 innosoft.com SMTP service ready
   C: EHLO dbc.mtview.ca.us
   S: 250-innosoft.com
   S: 250 PIPELINING
   C: MAIL FROM:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: RCPT TO:<[e-mail]>
   C: DATA
   S: 250 sender <[e-mail]> OK
   S: 550 remote mail to <[e-mail]> not allowed
   S: 550 remote mail to <[e-mail]> not allowed
   S: 354 enter mail, end with line containing only "."
   C: .
   C: QUIT
   S: 554 no valid recipients
   S: 221 goodbye

6.  Security Considerations

   This document does not discuss security issues and is not believed to
   raise any security issues not endemic in electronic mail and present
   in fully conforming implementations of [1].

7.  Acknowledgements

   This document is based on the SMTP service extension model presented
   in RFC 1425. Marshall Rose's description of SMTP command pipelining
   in his book "The Internet Message" also served as a source of
   inspiration for this extension.

8.  References

   [1]  Postel, J., "Simple Mail Transfer Protocol", STD 10,
        RFC 821, August 1982.

   [2]  Klensin, J., Freed, N., Rose, M., Stefferud, E., and
        D. Crocker, "SMTP Service Extensions", RFC 1869,
        November 1995.

   [3]  Freed, N., "SMTP Service Extension for Command Pipelining",
        RFC 1854, October 1995.




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RFC 2197                 SMTP Service Extension           September 1997


   [4]  Bradner, S., "Key words for use in RFCs to Indicate
        Requirement Levels", RFC 2119, March 1997.

9.  Author's Address

   Ned Freed
   Innosoft International, Inc.
   1050 Lakes Drive
   West Covina, CA 91790
   USA

   Phone: [phone]
   Fax: [phone]
   EMail: [e-mail]

   This document is a product of work done by the Internet Engineering
   Task Force Working Group on Messaging Extensions, Alan Cargille,
   chair.

































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