Always Learning wrote:
> Martin A. Brooks wrote on Fri, 23 Apr 2010 16:49:15 +0100.
>
>
>> 550-[C06.5] IP host name invalid for normal mail server.
>
> 2010-04-23 16:43:25
> H=olga.hinterlands.org [212.13.195.161]:55476
>
> rejected [C06.5] IP host name invalid for normal mail server.
>
>> What does "IP host name invalid for normal mail server" actually mean?
>
> The test in Exim is
>
> deny message = [C06.5] Msg6 Msg2
> hosts = ^.*[a].?[d].?[s].?[l]*
>
> and is intended to reject mail from mail servers having 'adsl' in the
> host name of their connection. 'olga.hinterlands.org' clearly does not
> have 'adsl' but does have 'ads' so I am changing the test to
>
> hosts = ^.*[a].?[d].?[s].?[l].?
>
> I thought, mistakenly perhaps, .? means none or only 1 ambiguous
> character.
>
>> I'd mail you directly to ask but..... :)
>
> You did have the phone number ............ :-)
>
> Regards,
>
> Paul.
>
You really don't need to go to that trouble - or risk of falsing. Anyway 'adsl'
is not all that consistently present even if you HAD properly matched for it.
Some say 'residential' and so forth.
Look at the source code in hosts.c for the Exim rDNS check. Note that it tries
to gather information to build, then vet, a list of possibilities - IOW seeks a
way to ascertain if the IP can be tracked to 'enough' information, even if
indirectly, (server pools exist) that a reasonable chance of successfully
exchanging smtp correspondence is out there.
Flexible, adaptive, even. Not draconian in and of itself.
But PA assigned IP that have no PTR RR are adroitly handled. 'coz no PTR RR
means no string or breadcrumb trail to track back. End of THAT story.
The *USE* of it is another matter, but still:
- You don't HAVE to use it with a 'require' or a 'deny' class verb
- a 'warn' and/or point-scoring will suffice if you prefer to taste and smell
spam and malware instead of simply avoiding it.
- Either way, it is *very* resistant to 'genuine' false-positives.
Best of all - it is built-in, in compiled C - and dead-simple to activate.
Bill
