RE: And so it begins...

1. We have several domains here at CrossCheck.  One mail server is hosting
all the domains e-mail using one IP address.  How can rDNS resolve to all
the domains to the same IP address.  Does rDNS give you a list of all the
associated domains?

2. We provided a service for retailers and acknowledge receipt of payment
from the retailer to the consumer.  So in effect we are SPAMming for a real
business reason.  This will never match the rDNS to the server's domains.

rDNS just does not cut the mustard alone.  It should add points to a total
score of SPAM filtering but not be a show stopper.

Chris Bipes

-----Original Message-----
From: Chuck Lewis [mailto:clewis@xxxxxxxxxx] 
Sent: Wednesday, April 13, 2005 5:48 AM
To: 'Midrange Systems Technical Discussion'
Subject: RE: And so it begins...


But rDNS isn't without issues too ?

>From
http://searchcio.techtarget.com/sDefinition/0,,sid19_gci917504,00.html:


Reverse DNS (rDNS) is a method of resolving an IP address into a domain
name, just as the domain name system (DNS) resolves domain names into
associated IP addresses. One of the applications of reverse DNS is as a spam
filter. Here's how it works: Typically, a spammer uses an invalid IP
address, one that doesn't match the domain name. A reverse DNS lookup
program inputs IP addresses of incoming messages to a DNS database. If no
valid name is found to match the IP address, the server blocks that message.

Although reverse DNS is fairly effective for filtering spam, it also
sometimes blocks valid e-mail, at least in the current technological
environment. A number of problems, including network delays and improperly
configured networks or servers, can prevent legitimate messages from getting
through the filter. In January 2003, AT&T WorldNet started using reverse DNS
in conjunction with other anti-spam software. The company was forced to
remove the filter just 24 hours after it was deployed, after subscribers
reported that messages were going undelivered.

So has the problem that AT&T WorldNet been fixed or is that still an issue ?