Network Working Group D. Royer
Internet-Draft INET-Consulting
Expires: December 13, 2003 June 14, 2003
IMAP-PROXY service for mobile clients to do submitting and forwarding
draft-royer-lemonade-submit-00
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This memo describes a method that allows mobile clients to use the
IMAP protocol and submit messages to a IMAP-PROXY service that
understands [E]SMTP and IMAP.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. SUBMIT command . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. CAPABILITY interception . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
As many mobile devices are both memory and bandwidth limited there
needs to be a way for mobile devices to forward and include existing
messages and body parts to others using email without downloading.
This is a memo released as part of the discussions on the 'LEMONADE'
working group. The idea is that a IMAP-PROXY service can sit on top
of an IMAP and [E]SMTP server in order to allow mobile devices the
ability to submit and retrieve e-mail through one port.
The basic idea is that the IMAP aware client sends normal IMAP
commands to the IMAP server and gets normal IMAP responses. The IMAP
client can not tell that it is passing through a IMAP-PROXY and
submit service.
How the messages and body part are included is not described in the
memo. The memo concentrates on the IMAP-PROXY service itself at the
functional level.
IMAP-PROXY servers that support this extension MUST list the keyword
CAN-SUBMIT in their CAPABILITY response. No client action is needed
to invoke the CAN-SUBMIT capability in a server.
2. Overview
The IMAP-PROXY service sits on top of both IMAP and an SMTP service.
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+---------+ +---------+
| STANDARD| | SUBMIT |
| IMAP | | IMAP |
| CLIENT | | CLIENT |
+---------+ +---------+
\ /
\ /
. .
. .
.
|
|
+----------+
| PROXY |
+----------+
/ \
/ \
| |
+------+ +------+
| IMAP | | SMTP |
|SERVER| |SERVER|
+------+ +------+
The IMAP-PROXY passes all IMAP commands (except SUBMIT) to the IMAP
server and passes all IMAP responses back to both the standard and
submit IMAP clients.
The SUBMIT command is intercepted by the IMAP-PROXY server. It reads
the contents of the message sent by the submit aware IMAP client,
includes or forward any messages as specified in the content of the
submit message. And send SUBMIT responses back to the SUBMIT aware
client.
3. SUBMIT command
Arguments: message literal
Responses: no specific responses for this command
Result: OK - append completed
NO - append error: can't send message.
BAD - command unknown or arguments invalid
The SUBMIT command submits the literal argument as a new message to
the users specified in the message. This argument MUST be in the
format of an [RFC-822] message. 8-bit characters are permitted in
the message. A server implementation that is unable to preserve 8-
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bit data properly MUST be able to reversibly convert 8-bit SUBMIT
data to 7-bit using a [MIME-IMB] content transfer encoding.
The IMAP-PROXY service may check and alter the SMTP headers to ensure
they conform to site requirements. This may include making sure the
'From:' line is valid within the site. Might include replacing the
Message-Id, removing any Received-By lines, Date, and so on.
A successful submit simply means that the SMTP server accepted all
recipients and the message for submission. Just like with any other
SMTP submission recipient errors will bounce back to the users INBOX.
Example: C: A003 SUBMIT {356}
C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
C: From: Fred Foobar <foobar@Blurdybloop.COM>
C: Subject: afternoon meeting
C: To: mooch@owatagu.siam.edu,badUser@example.com,
unknownUser@example.com
C: Message-Id: <B27397-0100000@Blurdybloop.COM>
C: MIME-Version: 1.0
C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
C:
C: Hello Joe, do you think we can meet at 3:30 tomorrow?
C:
S: A003 OK SUBMIT completed
If there is an SMTP error the IMAP-PROXY service returns any message
followed by any unacceptable recipients. The message is a comma
separated string with the non-recipient errors listed first followed
by one or more recipients that are invalid. A NO response indicates
that no message was sent to any recipient.
This example two users were rejected. The first message
section is empty (message starts with a comma).
S: A123 NO ,badUser@example.com,unknownUser@example.com
An error message not specific to any user. The non
recipient part of the message must not include a comma
as a comma separates the parts of the error message.
And the comma is not part of the message itself.
S: A445 NO MX server not responding,
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4. CAPABILITY interception
The IMAP-PROXY intercepts the CAPABILITY response from the IMAP
server and adds the CAN-SUBMIT capability to the list.
Author's Address
Doug Royer
INET-Consulting.com
1795 W. Broadway #266
Idaho Falls, Idaho 83402
US
Phone: 208-520-4044
Fax: 866-594-8574
EMail: Doug@Royer.com
URI: http://Royer.com/People/Doug
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Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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