[ On Sunday, December 8, 2002 at 14:24:14 (-0500), James P. Roberts wrote: ]
> Subject: Re: [Exim] Example of legit email rejected by testing on reverse IP lookup
>
> If you forward lookup my server, it returns the correct IP address. It
> is only the reverse DNS, currently outside my control, which is screwed
> up. But at least an entry exists.
It's much better to have no reverse-DNS than to have incorrect reverse-DNS.
Now what you have is only partly incorrect since there is a valid
hostname for the PTR target.
Totally incorrect reverse DNS causes all kinds of failures with many
services, including SMTP. I.e. if the PTR does not point at a hostname
which will resolve to the same IP address the reverse DNS lookup was
derrived from then you would be screwed, to put it semi-politely.
Partialy incorrect reverse DNS isn't quite so bad -- it doesn't help
anyone really trust your hostname for which there's no PTR, but if your
hostname doesn't enter into the picture then most servers will be happy.
I.e. you should have your mailer announce itself in its SMTP greeting
with the *.covad.net name. That way nobody can complain that it's not
giving the correct and canonical hostname for its IP address.
Missing referse DNS usually only causes delays. Anyone insisting on
reverse DNS for foreign SMTP clients is really running a very
restrictive server -- far more restrictive than even my own home server! :-)
--
Greg A. Woods
+1 416 218-0098; <g.a.woods@???>; <woods@???>
Planix, Inc. <woods@???>; VE3TCP; Secrets of the Weird <woods@???>
