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Simple Mail Transfer Protocol (SMTP). Name: Chaitanya Krishna Telukuntla Date : 04-24-2007. Introduction. Objective is to transfer mail reliably and efficiently independent of particular transmission system
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Simple Mail Transfer Protocol (SMTP) Name: Chaitanya Krishna Telukuntla Date : 04-24-2007
Introduction • Objective is to transfer mail reliably and efficiently • independent of particular transmission system • feature is its capability to relay mail across transport service environment by interprocess communication environment (IPCE)
SMTP Model Commands/replies & mail Sender SMTP Receiver SMTP user File system File system
Requests, Parameters and Responses • Request format: HELO yahoo.com • Response format: 250-yahoo.com 250-PIPELINING 250 8BITMIME
Encoded addresses • Encoded box parts: angels \a\n\g\e\l\s "\a\n\g\e\l\s" "angels" "ang\els" • Encoded address: <xy@cs.odu.edu> <\xy@cs.odu.edu> <"xy"@gmail.com> <"\x\y"@yahoo.com>
MAIL, RCPT and DATA • Server keeps track of envelope for the client 220 gmail.com ESMTP MAIL FROM:<pqr@yahoo.com> 250 ok RCPT TO:<xy@gmail.com> 250 ok RCPT TO:<ab@gmail.com> 250 ok • Argument to MAIL command is reverse path • Argument to RCPT command is forward path
DATA: MAIL FROM:<pqr@yahoo.com> 250 ok RCPT TO:<xy@gmail.com> 250 ok DATA 354 ok Hi, testing new mail system. . 250 Written safely to disk
QUIT QUIT 221 gmail.com saying goodbye
Typical SMTP Scenario S:220 gmail.com SMTP service ready C:HELO yahoo.com S:250 gmail.com says hello to yahoo.com C: MAIL FROM:<pqr@yahoo.com> S: 250 ok C: RCPT TO:<xy@gmail.com> S: 250 ok FROM: pqr@yahoo.com TO:xy@gmail.com MIME-version:1.0 Message-id: <0704760941.AA00747 @yahoo.com> C:DATA S:354 Send mail; end with “.” on a line by itself C: Hi C: how are you? C: . S:250 ok C:QUIT S:gmail.com closing connection