本节提供了一些smtp会话的完整例子。
典型的smtp操作
此类显示邮件如何由在usc-isif和机上的smith发送到bbn-unix主机上jones，green和brown的。这里，我们假设usc-isif主机直接和bbn-unix主机联系。jones和brown接收邮件，而green在bbn-unix上没有邮箱。
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r: 220 bbn-unix.arpa simple mail transfer service ready
s: helo usc-isif.arpa
r: 250 bbn-unix.arpa
s: mail from:<smith@usc-isif.arpa>
r: 250 ok
s: rcpt to:<jones@bbn-unix.arpa>
r: 250 ok
s: rcpt to:<green@bbn-unix.arpa>
r: 550 no such user here
s: rcpt to:<brown@bbn-unix.arpa>
r: 250 ok
s: data
r: 354 start mail input; end with <crlf>.<crlf>
s: blah blah blah...
s: ...etc. etc. etc.
s: .
r: 250 ok
s: quit
r: 221 bbn-unix.arpa service closing transmission channel
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放弃smtp操作
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r: 220 mit-multics.arpa simple mail transfer service ready
s: helo isi-vaxa.arpa r: 250 mit-multics.arpa
s: mail from:<smith@isi-vaxa.arpa>
r: 250 ok
s: rcpt to:<jones@mit-multics.arpa>
r: 250 ok
s: rcpt to:<green@mit-multics.arpa>
r: 550 no such user here
s: rset
r: 250 ok
s: quit
r: 221 mit-multics.arpa service closing transmission channel
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转发邮件
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第一步：源主机到转发主机
r: 220 usc-isie.arpa simple mail transfer service ready
s: helo mit-ai.arpa
r: 250 usc-isie.arpa
s: mail from:<jqp@mit-ai.arpa>
r: 250 ok
s: rcpt to:<@usc-isie.arpa:jones@bbn-vax.arpa>
r: 250 ok
s: data
r: 354 start mail input; end with <crlf>.<crlf>
s: date: 2 nov 81 22:33:44
s: from: john q. public <jqp@mit-ai.arpa>
s: subject: the next meeting of the board
s: to: jones@bbn-vax.arpa
s:
s: bill:
s: the next meeting of the board of directors will be
s: on tuesday.
s: john.
s: .
r: 250 ok
s: quit
r: 221 usc-isie.arpa service closing transmission channel
第二步：转发主机到目的主机
r: 220 bbn-vax.arpa simple mail transfer service ready
s: helo usc-isie.arpa
r: 250 bbn-vax.arpa
s: mail from:<@usc-isie.arpa:jqp@mit-ai.arpa>
r: 250 ok
s: rcpt to:<jones@bbn-vax.arpa>
r: 250 ok
s: data
r: 354 start mail input; end with <crlf>.<crlf>
s: received: from mit-ai.arpa by usc-isie.arpa ;
2 nov 81 22:40:10 ut
s: date: 2 nov 81 22:33:44
s: from: john q. public <jqp@mit-ai.arpa>
s: subject: the next meeting of the board
s: to: jones@bbn-vax.arpa
s:
s: bill:
s: the next meeting of the board of directors will be
