--On 4 March 2008 15:45:08 +0000 Paulo Almeida <palmeida@???> wrote:
>> Actually, the problem isn't solved, since the problem was with the
>> recipient's callouts. They should be checking all your MX servers. They
>> should not be hard failing on a temporary error.
>>
>> Who was the recipient?
>
> Hi Ian,
>
> We could not send any email to ua.pt domain.
> In response to MAIL FROM for our mail server (MAIL FROM:<example@???>
> for example), they refuse it with a 572 error: example@??? host name
> is unknown.
>
> But, if i telnet MAIL FROM:<example@???>, they accept the
> message. In this case, recipient was postmaster@???
>
> What i understand, is that they make some kind of host/sender verification
> policy, by testing if the right part at '@' is a valid host.
> esenf.pt is not a real host, but mail.esenf.pt is (our mail server).
>
> Tom Kistner advise me that maybe the reason was the our lowest priority MX
> server point to a fake address (host mx0.esenf.pt not found:
> 3(NXDOMAIN)). I remove that entry in dns and the messages start to be
> accepted.
> Like you say, i suppose too that they should checking all ours mx servers,
> but apparently if they received a failed response at first time they
> refuse the message.
>
> I'm not a truly mx expert, so what is going wrong here?
I think your MX records can be regarded as broken if they point to an host
without an A record. Create a DNS A record for mx0.esenf.pt, and you should
be OK. It needs to point to an IP address that you own, but you don't have
to have a mail server listening at that IP address.
UA.PT should then check your next highest priority address, and the callout
should succeed. My guess is that they aren't actually doing a callout,
they're failing you for having broken MX records.
> Regards,
> Paulo Almeida
>
> --
> Escola Superior de Enfermagem do Porto
> Rua Dr. António Bernardino de Almeida
> 4200-072 Porto - Portugal
> Tel: +351 22 5073500 - Fax: +351 22 5096337
> http://portal.esenf.pt
>
>
>
> --
> Escola Superior de Enfermagem do Porto
> Rua Dr. António Bernardino de Almeida
> 4200-072 Porto - Portugal
> Tel: +351 22 5073500 - Fax: +351 22 5096337
> http://portal.esenf.pt
--
Ian Eiloart
IT Services, University of Sussex
x3148
