> -----Original Message-----
> From: exim-users-bounces@??? [mailto:exim-users-bounces@exim.org] On Behalf Of Craig Whitmore
> Sent: Wednesday, August 24, 2011 8:32 AM
> To: Oliver Howe; exim-users@???
> Subject: Re: [exim] listed at .backscatterer.org
>
> A mail server should not accept emails if it cannot deliver it so
> accepting emails for invalid users and then bouncing it is wrong.
That's a troublesome requirement. If user validation can't be done at the border, or especially if there's a validation service in between the sender and the receiving domain, a domain has no choice but to do this.