[RFCI-Discuss] multi-MAIL commands appearing in the same mail-transaction?

Tue Jun 6 08:34:10 EDT 2006

>> When I read RFC2821,I saw that it permit multi-MAIL FROM commands appear in the same mail transaction.
>> For example:
>> 
>> HELO abcd.163.com
>> MAIL FROM:<abc at 163.com>
>> MAIL FROM:<def at 163.com>
>> ....
>
>Where does it say this?

Hello,I saw them in RFC2821 below:

      The first step in the procedure is the MAIL command.  The
        <reverse-path> contains the source mailbox.

           MAIL <SP> FROM:<reverse-path> <CRLF>

        This command tells the SMTP-receiver that a new mail
        transaction is starting and to reset all its state tables and
        buffers, including any recipients or mail data.  It gives the
        reverse-path which can be used to report errors.  If accepted,
        the receiver-SMTP returns a 250 OK reply.

        The <reverse-path> can contain more than just a mailbox.  The
        <reverse-path> is a reverse source routing list of hosts and
        source mailbox.  The first host in the <reverse-path> should be
        the host sending this command.

It say 'The <reverse-path> can contain more than just a mailbox'.As I think,each mailbox mean a MAIL FROM command,so there would permit multi-MAIL commands.Is it right?

When I test gmail's mx,I saw it's successful,as below:

[coremail at admin ~/hlj]$ telnet alt1.gmail-smtp-in.l.google.com 25
Trying 64.233.185.27...
Connected to alt1.gmail-smtp-in.l.google.com.
Escape character is '^]'.
220 mx.gmail.com ESMTP g3si577842wra
helo 163.com
250 mx.gmail.com at your service
mail from:<abcd at 163.com>
250 2.1.0 OK
mail from:<efgh at 163.com>
250 2.1.0 OK
rcpt to:<xxxx at gmail.com>
250 2.1.5 OK
data
354 Go ahead
from:<abcd at 163.com>
to:<xxxx at gmail.com>
subject:helo,test.

it's a test mail for jeff peng from 163.com.
.
250 2.0.0 OK 1149596882 g3si577842wra
quit

When I open my gmail and see that message's original header,I got:

Received-SPF: pass (gmail.com: domain of efgh at 163.com designates 220.181.15.241 as permitted sender)
Date: Tue, 06 Jun 2006 05:28:02 -0700 (PDT)
Message-Id: <448574d2.5e02da67.63de.ffffeae3SMTPIN_ADDED at mx.gmail.com>
from: <abcd at 163.com>
to: <xxxx at gmail.com>
subject: helo,test.

Notice here: 
Return-Path: <efgh at 163.com>

It seems that the second MAIL FROM has overcovered the first MAIL FROM.
It's somewhat confused for me,I think.

--
Jeff Pang
NetEase AntiSpam Team
http://corp.netease.com