Re: [EXIM] Empty MAIL FROM

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Author: Philip Hazel
Date:  
To: Mike Zanker
CC: exim-users
Subject: Re: [EXIM] Empty MAIL FROM
On Fri, 28 Nov 1997, Mike Zanker wrote:

> I've just noticed that when Exim is sending a delivery error report it uses
> a blank envelope from address (MAIL FROM:<>). Is this intentional?
>
> Some mail hosts are rejecting them because of this (sprintmail.com MX hosts
> for example).


Those hosts are broken. From RFC 1123:

      5.2.9  Command Syntax: RFC-821 Section 4.1.2


         The syntax shown in RFC-821 for the MAIL FROM: command omits
         the case of an empty path:  "MAIL FROM: <>" (see RFC-821 Page
         15).  An empty reverse path MUST be supported.


      ...


      5.3.3  Reliable Mail Receipt


         ...


         If there is a delivery failure after acceptance of a message,
         the receiver-SMTP MUST formulate and mail a notification
         message.  This notification MUST be sent using a null ("<>")
         reverse path in the envelope; see Section 3.6 of RFC-821.  The
         recipient of this notification SHOULD be the address from the
         envelope return path (or the Return-Path: line).  However, if
         this address is null ("<>"),  the receiver-SMTP MUST NOT send a
         notification.  If the address is an explicit source route, it
         SHOULD be stripped down to its final hop.



-- 
Philip Hazel                   University Computing Service,
ph10@???             New Museums Site, Cambridge CB2 3QG,
P.Hazel@???          England.  Phone: +44 1223 334714



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