Re: [exim] HELO name problems

On 2009-08-15 Ross Boylan <ross@???> wrote:
> On Sat, 2009-08-15 at 09:34 +0200, Andreas Metzler wrote:
>> Ross Boylan <ross@???> wrote:
>>> On Thu, 2009-08-13 at 20:46 +0100, Mike Cardwell wrote:
[...]
>>>> helo_data = upstrm185.psg-ucsf.org
[...]

>> you could use a dnsdb lookup to keep it up to date automatically.

>> helo_data = ${lookup dnsdb {ptr=$sending_ip_address}{$value}{$primary_hostname}}
> Does this impose much of an extra load?

Hello,

I /think/ the extra overhead should be low if you are running a local
caching DNS server which afaik is best practice anyway when running a
SMTP server.

> exim says it caches queries but it's not clear if that includes dnsdb,
> or that it should. Also the cache is only per process. Similarly DNS
> also caches. I don't know how much different that makes, esp if there
> is some DNS failure.

defer_never is probably a must, however I guess a failure to resolve will
slow down things a lot.

> Also, the IP address could change as well as the name.

$sending_ip_address will change accordingly.
cu andreas

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