Postfix Address Verification

[Seamus Allan]

Drew Marshall wrote:
> This looks like a DNS problem. Are you running a cacheing DNS server on
> this box? Postfix is rejecting with a temporary failure (450) as it is
> having what it thinks could be a short term problem. I assume you have set
> the next hop in the transport map file, have you done this using a name
> record or IP address? i.e. in the file does it say:
>
> validdomain  relay:internal.host
>
> or
>
> validdomain  relay:[192.168.1.225]
>
> Just to make sure this isn't Postfix logging a slight red herring, can you
> also let me know what you have under:
>
> smtpd_client_restrictions
> smtpd_sender_restrictions
>
> in main.cf
>
> The other thing to check is the logs of the internal machine (Exchange?),
> just in case there is anything obvious there.
>
> Drew
>
>
>   
Hi,

I am not running a caching DNS server on this box, all DNS queries are 
passed to our internal DNS server, however this shouldn't be an issue, 
as you noted because the next hop is dictated by an entry in the 
transport map, using IP based hosts. This is what I find so confusing, 
surely Postfix uses this transport map or even the relay_domain map to 
decide whether a domain is valid or not?
I did spend the other day looking at the internal mail hub, and there is 
nothing out of the ordinary in there which would indicate a problem 
(such as SMTP restrictions because of connection rate or something).
In my main.cf, I don't have entries for smtpd_client_restrictions or 
smtpd_sender_restrictions (whether this is bad or not?), and my 
smtp_receipient_restrictions is as follows:
smtpd_recipient_restrictions = permit_mynetworks, 
permit_sasl_authenticated, reject_unauth_destination, 
reject_non_fqdn_recipient, reject_unknown_recipient_domain, 
reject_unverified_recipient

It all seems rather tricky, as there is nothing obvious as to why this 
his happening.

Cheers for the help


Seamus

*Seamus Allan*
Network Engineer
Rheel Electronics Ltd