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SMTP

SMTP is a protocol used to transfer email between servers. It uses commands like MAIL FROM, RCPT TO, and DATA to send messages. SMTP is a push protocol that sends email, while POP3 and IMAP are used to retrieve email. SMTP can operate in either an end-to-end or store-and-forward model to transfer messages between client and server.

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118 views19 pages

SMTP

SMTP is a protocol used to transfer email between servers. It uses commands like MAIL FROM, RCPT TO, and DATA to send messages. SMTP is a push protocol that sends email, while POP3 and IMAP are used to retrieve email. SMTP can operate in either an end-to-end or store-and-forward model to transfer messages between client and server.

Uploaded by

pankaj
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PPT, PDF, TXT or read online on Scribd
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SMTP

Simple mail transfer client


SMTP
• Email is emerging as the one of the most
valuable service in internet today. Most of the
internet systems use SMTP as a method to
transfer mail from one user to another. SMTP
is a push protocol and is used to send the mail
whereas POP (post office protocol) or IMAP
(internet message access protocol) are used
to retrieve those mails at the receiver’s side.
• It Is a protocol that defines MTA client and
server in the internet.
MODEL of SMTP
Range of SMTP
• Range of SMTP upto receiver mail server.
• Will use some protocol to send message from
mail server to babu.
• SMTP uses commands and responses to
transfer messages between an MTA client and
MTA server.
Example of commands
• HELO .Used by client to identify itself

• Mail from .identify sender


.
• RCPT TO: .identify intented receipient

• DATA: .send actual messsage


• QUIT . Quit->terminate the message
• RSET .Reset the connection
• VRFY .Verify the add of receipient
• HELP .HELP: mail( receipient will send information related to mail
command)
Example of responses
• Positive condition reply
• Transient negative completion reply
• Permanent negative completion reply
Positive condition reply
• 211- system status
• 214-help
• 220-service ready
• 221-service closing
Transient negative completion reply
• 421-service NA
• 450-mailbox NA
• 451-command Aborted
Permanent negative completion reply
• 500- syntax error
• 554 – transaction failed
MAIL Transfer PHASES
1. Connection establishment
2. Message transfer
3. Connection termination
Connection establishment
Message transfer
Connection termination
SMTP Protocol
• The SMTP model is of two type :
• End-to- end method
• Store-and- forward method
End to end
• The end to end model is used to communicate
between different organizations whereas the
store and forward method is used within an
organization. A SMTP client who wants to
send the mail will contact the destination’s
host SMTP directly in order to send the mail to
the destination. The SMTP server will keep the
mail to itself until it is successfully copied to
the receiver’s SMTP.
Store and forward
• The client SMTP is the one which initiates the
session let us call it as client- SMTP and the
server SMTP is the one which responds to the
session request and let us call it as receiver-
SMTP. The client- SMTP will start the session
and the receiver-SMTP will respond to the
request.

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