How does SMTP work

[neemitjamwal]

Cna any one enlightn me on how does SMTP manages the transfer of files from one host computer system to another

[skiddieleet]

To understand it you kindof have to understand tcp/ip in general. Check out this movie:
http://www.warriorsofthe.net/movie.html
If you have dialup, I would pass on that and just go to the tutorials forum and read some of the tcp/ip tutorials. Basically it just takes the email address and associates that with the smtp server for that email address. It sends some information to that smtp server which then puts the email in the correct inbox based on the info from the sending smtp server.

[groovicus]

If you have some time for some heavy reading...try this http://www.ietf.org/rfc/rfc0821.txt

[w0lverine]

The simple mail transfer protocol (SMTP) manages the transfer of mail from one host computer mail system to another. It is not responsible for accepting mail from local users or for distinguishing received mail to its intended recipient(s). These are the responsibility of the local mail system. The interrelationship between SMTP.
Since SMTP interacts with the local mail system and not the user, it is masked from any mail transfers local to the machine. Only when an item of mail is to be sent to a different machine or is received from a remote machine is the SMTP scheduled to run. Normally, there is an input queue and an output queue at the interface between the local mail system – often referred to as the native mail system – and the client and the server parts of the SMTP. The client is concerned with receiving mail.
SMTP is very simple, where the communication between the client and the server is in the form of readable ASCII text. Initially, the client establishes a reliable stream connection to the server and waits for the server to respond with a 220 READY FOR MAIL message. On receipt of 220 message the client sends a HELO message. The server then responds by identifying itself. Once the connection has been established, the sender can transmit the messages, terminate the connection or even request the server to switch the role of the receiver and the sender so that the messages can flow in the opposite direction. It can also abort the current message transfer or the entire connection. The receiver must acknowledge all the messages received.

Mail transaction begins with the MAIL command that gives the sender's identification. Also there is a FROM: field that specifies the address to which all the errors must be reported. The receiver then prepares to receive the messages and then sends a 250 OK command telling everything is ok.

After successful completion of the MAIL command the sender will issue a series of RCPT command that will identify the receiver. The receiver must acknowledge all the commands with a 250 OK or an error message. After all the RCPT commands have been executed, the sender sends a DATA command, that basically tells the receiver that the sender is ready to transmit the messages. The receiver then responds with a 350 Start Mail Input and the sequence of characters that will be used to terminate the message.

SMTP itself does not define the way these errors should be handled. It is for the client to decide whether to abort the transmission, or to continue the transmission to all the valid recipients and then report the errors to the original sender. The report contains a summary of the error and the header of the message.

The roles of the sender and the receiver can be switched by issuing the TURN command. The other side must respond with a 250 OK command. The side that controls the interaction can terminate the connection by issuing the QUIT command.

[lumpyporridge]

If you want to see the workings of smtp, why not install and run http://www.ethereal.com/ and then send/receive some email. You will see exactly how it works on a packet level.

[Striek]

Originally posted here by w0lverine
The simple mail transfer protocol (SMTP) manages the transfer of mail from one host computer mail system to another.

See http://foe.mmu.edu.my/course/ecp3086.../Chapter4c.doc

It is generally considered polite to quote your sources when plagarising them.

[akshayakrsh]

think i got a solution for that! and not only that if u want to know about working of anything you can just visit the website:


www.howstuffworks.com

happy surfing