[ On Wednesday, April 9, 2003 at 17:16:28 (+0100), Philip Hazel wrote: ]
> Subject: RE: [Exim] conditionally rejecting <> sender
>
> There are cases that will break:
>
> 1. If you use an Exim filter, you can use commands like
>
> mail to "a@b, x@y"
>
> to create messages with multiple recipients, but NULL senders.
Such a filter is broken by design! ;-)
> 2. More obscure, probably unlikely:
>
> . You send out mail with envelope sender as postmaster@???.
> . The delivery fails somewhere down the line, causing a bounce to come back.
> . You have "postmaster" aliased to more than one address.
> . Both addresses get forwarded to some other host that is enforcing this
> check...
This is a generic problem with aliases and the way they're sometimes
implemented in MTAs. The error bounces for aliases should never go to
the original sender, but rather always only to someone who can fix the
broken alias. I.e. the sender address for a message re-directed by an
alias should always be re-mapped to be the owner address for that alias
(e.g. to follow the sendmail style: <owner-alias@???>). This
implies that by default <owner-*@domain> should be re-directed to
<postmaster@domain> in case no more specific owner address is given.
--
Greg A. Woods
+1 416 218-0098; <g.a.woods@???>; <woods@???>
Planix, Inc. <woods@???>; VE3TCP; Secrets of the Weird <woods@???>
