Re: [exim] Remote domain not found in DNS

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Author: Matthew Newton
Date:  
To: Dean Brooks
CC: exim-users
Subject: Re: [exim] Remote domain not found in DNS
On Tue, Oct 25, 2005 at 12:43:20PM -0400, Dean Brooks wrote:
> On Tue, Oct 25, 2005 at 06:33:20PM +0200, David Saez Padros wrote:
>
> > verify       = header_sender/callout=10s/defer_ok

> >
> > gives the error
> >
> > could not verify "From:" header address
> > 550 stefan@???: Remote domain not found in DNS
> >
> > altough webau1.hostcore.com.au does not have MX records it has
> > an A record and thus should not give that error.
>
> If there are no MX records, how can webau1.hostcore.com.au possibly
> be a valid email address? The verify header_sender specifically
> checks for a valid email address, but without MX records, it is
> not valid.
>
> This seems to be working as intended from what I can tell.


However, RFC2821, section 5:

"The lookup first attempts to locate an MX record associated
with the name. If a CNAME record is found instead, the
resulting name is processed as if it were the initial name. If
no MX records are found, but an A RR is found, the A RR is
treated as if it was associated with an implicit MX RR, with a
preference of 0, pointing to that host."

Which seems to imply to me that A records should be searched for
if MXes do not exist (that is always the was I understood that it
worked).

Matthew


--
Matthew Newton <mcn4@???>

UNIX and e-mail Systems Administrator, Network Support Section,
Computer Centre, University of Leicester,
Leicester LE1 7RH, United Kingdom