SMTP: Difference between revisions
From Leo's Notes
This page was last edited on 15 June 2020, at 00:09.
Created page with "Simple Mail Transport Protocol (SMTP) == Other == === HELO vs. EHLO === The greeting used by SMTP is typically a {{code|HELO}} or {{code|ELHO}}. HELO is defined in RFC 821,..." |
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== Other == | == Other == | ||
=== Transport Example === | |||
A client may send the following to a SMTP server. | |||
{{highlight|lang=terminal|code= | |||
EHLO mail.steamr.com | |||
MAIL FROM:<dude@steamr.com> | |||
RCPT TO:<alex@steamr.com> | |||
DATA | |||
From: "Cool Dude" <dude@example.com> | |||
To: "Mister Alex" <alex@steamr.com> | |||
Cc: alice@steamr.com | |||
Date: Mon, 23 Sept 2019 22:19:00 -0600 | |||
Subject: Hello | |||
Hello. | |||
This is a test message | |||
Bye! | |||
. | |||
QUIT | |||
}} | |||
=== HELO vs. EHLO === | === HELO vs. EHLO === | ||
The greeting used by SMTP is typically a {{code|HELO}} or {{code|ELHO}}. HELO is defined in RFC 821, published back in 1982 when mail was actually simple and without additional protocols and mechanisms like TLS or odd authentication schemes. EHLO is defined in RFC 2821 which was published in 2001 with the expectation that the response contains multiple lines containing keywords and parameters. | The greeting used by SMTP is typically a {{code|HELO}} or {{code|ELHO}}. HELO is defined in RFC 821, published back in 1982 when mail was actually simple and without additional protocols and mechanisms like TLS or odd authentication schemes. EHLO is defined in RFC 2821 which was published in 2001 with the expectation that the response contains multiple lines containing keywords and parameters. | ||
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* https://www.ietf.org/rfc/rfc0821.txt | * https://www.ietf.org/rfc/rfc0821.txt | ||
* https://www.ietf.org/rfc/rfc2821.txt | * https://www.ietf.org/rfc/rfc2821.txt | ||
[[Category:Networking]] | |||
Latest revision as of 00:09, 15 June 2020
Simple Mail Transport Protocol (SMTP)
Other
Transport Example
A client may send the following to a SMTP server.
EHLO mail.steamr.com
MAIL FROM:<dude@steamr.com>
RCPT TO:<alex@steamr.com>
DATA
From: "Cool Dude" <dude@example.com>
To: "Mister Alex" <alex@steamr.com>
Cc: alice@steamr.com
Date: Mon, 23 Sept 2019 22:19:00 -0600
Subject: Hello
Hello.
This is a test message
Bye!
.
QUIT
HELO vs. EHLO
The greeting used by SMTP is typically a HELO or ELHO. HELO is defined in RFC 821, published back in 1982 when mail was actually simple and without additional protocols and mechanisms like TLS or odd authentication schemes. EHLO is defined in RFC 2821 which was published in 2001 with the expectation that the response contains multiple lines containing keywords and parameters.
With the new RFC 2821, clients are expected to use the newer ELHO command and servers are expected to support both.
Example output from both HELO and ELHO. (As per the RFC, keywords are case-insensitive).
helo vps.steamr.com
250 vps.steamr.com Hello vps.steamr.com [::1]
ehlo vps.steamr.com
250-vps.steamr.com Hello vps.steamr.com [::1]
250-SIZE 52428800
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN
250-STARTTLS
250 HELP
See: