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Re: Strange determination of an error address in Zmailer 2.1.2

On Thu, 12 Oct 1995, John Gardiner Myers wrote:

> 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.

  No one disagrees that error noticification should have the return path 
of <>, but the question has been how to find who to send the notification to.

  Yes, I'm wrong about using Sender: (if available) all the time.  This is 
appropiate (mostly) for non-SMTP systems that use RFC-822 messages, but this 
what Zmailer seems to do all the time.