Application Layer

Question

Is SMTP connection-oriented or connectionless ?

Comments

Since SMTP primarily uses TCP, it should be connection oriented. 

See this: https://stackoverflow.com/questions/16809214/is-smtp-based-on-tcp-or-udp

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i thought it is connectionless

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SMTP is connection oriented protocol which uses tcp for reliability,because SMTP is used as MTA(message transfer agent)which is push the message from client1 to mail server .then SMTP again push the message client 1 mail server to client 2 mail server .when message is reached the client 2 mail server then POP3 /IMAP protocol is used to pull the message from mail server to client 2.both protocol uses tcp for reliability of messages.

Answer 1

SMTP is a connection-oriented, text-based protocol in which a mail sender communicates with a mail receiver by issuing command strings and supplying necessary data over a reliable ordered data stream channel, typically a Transmission Control Protocol (TCP) connection.