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| email:smtp_transaction [2016/11/04 15:47] – peter | email:smtp_transaction [2019/11/27 22:09] (current) – removed peter |
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| ====== Email - SMTP Transaction ====== | |
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| Simple SMTP dialogue | |
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| ^ Client ^ Server ^ | |
| | Initiates a TCP connection to server. | Presents an SMTP banner - that is, a greeting that starts with the code 220 to indicate that it is ready to speak SMTP (or usually ESMTP, a superset of SMTP):\\ <WRAP BOX cyan> 220 your.f.q.d.n ESTMP... </WRAP> | | |
| | Introduces itself by way of an Hello command, either HELO (now obsolete) or EHLO, followed by its own Fully Qualified Domain Name:\\ <WRAP box cyan> EHLO peers.f.q.d.n </WRAP> | Accepts this greeting with a 250 response. If the client used the extended version of the Hello command (EHLO), your server knows that it is capable of handling multi-line responses, and so will normally send back several lines indicating the capabilities offered by your server:\\ \\ <WRAP box cyan> \\ 250-your.f.q.d.n Hello ...\\ 250-SIZE 52428800\\ 250-8BITMIME\\ 250-PIPELINING\\ 250-STARTTLS\\ 250-AUTH\\ 250 HELP\\ </WRAP> \\ \\ If the **PIPELINING** capability is included in this response, the client can from this point forward issue several commands at once, without waiting for the response to each one. | | |
| | Starts a new mail transaction by specifying the Envelope Sender:\\ <WRAP box cyan>MAIL FROM:<sender@address></WRAP> | Issues a **250** response to indicate that the sender is accepted. | | |
| | Lists the Envelope Recipients of the message, one at a time, using the command:\\ <WRAP box cyan>RCPT TO:<receiver@address></WRAP> | Issues a response to each command (**2xx**, **4xx**, or **5xx**, depending on whether delivery to this recipient was accepted, subject to a temporary failure, or rejected). | | |
| | Issues a **DATA** command to indicate that it is ready to send the message. | Responds **354** to indicate that the command has been provisionally accepted. | | |
| | Transmits the message, starting with RFC 2822 compliant header lines (such as: From:, To:, Subject:, Date:, Message-ID:). The header and the body are separated by an empty line. To indicate the end of the message, the client sends a single period (".") on a separate line. | | | |
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