Re: Strange determination of an error address in Zmailer 2.1.2

[John Gardiner Myers <jgm+@CMU.EDU>]

Matti Aarnio <mea@utu.fi> writes:
>         The Algorithm within router is such that when it needs to
>         look up for an error return address, it picks them in order:
> 
>                 Sender: ...
>                 Errors-To: ...
>                 MAIL FROM:<...>
> 
>         ( router/rfc822.c:erraddress() )
> 
>         This, like Tom Samplonius noted, is according to RFC-822...
>         (Well, "Errors-To:" I could not find..)

Absolutely incorrect.  From RFC 1123, section 5.3.3:

         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.

Transport agents should always user the envelope return path given
in the MAIL FROM: command for notification messages.

A subtlety is that when the envelope return path is null ("<>"), the
notification should be sent to the local postmaster.  Otherwise, when
mail arrives with invalid addresses in both the forward and reverse
paths, it will be silently discarded.

-- 
_.John G. Myers		Internet: jgm+@CMU.EDU
			LoseNet:  ...!seismo!ihnp4!wiscvm.wisc.edu!give!up