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:
> >> Ross Boylan wrote:
>
> >> > helo_data = ${if match_domain{$host}{*.alioth.debian.org}{upstrm185.psg-ucsf.org}{$primary_hostname}}
>
> >> > Is there a better solution? Will the previous modification work?
> [...]
> >> If you can't change the DNS, why not just change the helo? You've
> >> already shown you know how to do it with helo_data. Why not just have this:
>
> >> helo_data = upstrm185.psg-ucsf.org
>
> > Our sysadmin is concerned that if the upstream name changes we'll be
> > need to change the rule again. The networking environment we have to go
> > through to reach the public IP is not under our control, and the folks
> > who do control it don't necessarily keep us informed.
>
> Hello,
>
> 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?
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.
Also, the IP address could change as well as the name.
Ross
