On Thu, Jan 02, 2003 at 05:52:09AM +0000, Graham Hillstomer wrote:

> We have had a interesting discussion about the practical use of
> reverse DNS lookups and I am wondering what the general thoughts are
> here in the newsgroup.
>
> It seems that some ISP's and large sites are using it and others are
> not and the ones that are have a near constant complaint queue from
> users about not receiving emails from known good senders. The problem
> always resides in that the senders DNS either is not responding with
> correct MX information, is to slow to respond and gets automatically
> rejected, or returns an error code like "11004" valid but no data.

I had similar problems a little (long) while ago when I forgot to
setup reverse DNS for my two domains (plug.cx and alfred.cx). I think
I tried to e-mail Greg Lehey (of FreeBSD fame), and his mail server
spat at me because of my ill-configured DNS.

It was quite a process (excentuated by our ex-ISP's lack of
competency) and I doubt that the average Joe would have been
bothered. I think Average Joe would expect the ISP to deal with this
without any prompting.

> Is using reverse DNS worth it stop x% of spammers or is it to much
> trouble?

Configure your servers so they work with *everyone* elses is the
general rule that I work by. You can't tell your user(s) that they
can't e-mail a certain person because their ISP's mail server isn't
correctly configured. You're bound to come across someone with a dodgy
mail server.

I'd be looking to employ other spam filtering techniques, like MAPS or
something. The price of subscription would be soon absorbed by the
number of complaints you wouldn't get from people who can't send or
receive from certain people.

So, in a one-word answer to your question, "No" :-)

   - andrew

-- 
| Andrew Reid [mailto:andrew.reidplug.cx]
| Overworked and Underpaid Network Monkey
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