RE: Reverse DNS

  • From: "John Tolmachoff \(Lists\)" <johnlist@xxxxxxxxxxxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Sat, 13 Nov 2004 13:52:16 -0800

Now, hold on Tom. I did not say they are bad. I said and mean it is bad to
use that as a reason to block.

However, in a weighting system, where dozens of tests are performed, it has
its place. On my systems, and those I consult on, failing a REVDNS test
equals 20% of the hold/quarantine rate, and only 13% of the delete weight.

John Tolmachoff
Engineer/Consultant/Owner
eServices For You


> -----Original Message-----
> From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxx]
> Sent: Saturday, November 13, 2004 12:51 PM
> To: [ExchangeList]
> Subject: [exchangelist] RE: Reverse DNS
> 
> http://www.MSExchange.org/
> 
> Its good to see that an ever increasing number of e-mail admins are
> understanding that reverse DNS lookups are bad. There are much much
> better and more reliable ways to blocking spam without blocking
> legitimate senders.
> 
> 
> Tom
> www.isaserver.org/shinder
> Tom and Deb Shinder's Configuring ISA Server 2004
> http://tinyurl.com/3xqb7
> MVP -- ISA Firewalls
> 
> 
> -----Original Message-----
> From: Shawn Moua [mailto:smoua@xxxxxxxxxxxxxxx]
> Sent: Friday, November 12, 2004 6:08 PM
> To: [ExchangeList]
> Subject: [exchangelist] RE: Reverse DNS
> 
> http://www.MSExchange.org/
> 
> Darran,
> 
> This will help block spam but will also block legitimate emails as well.
> I would advise you to not use it because of this very reason.  There are
> a lot of businesses out there that don't have reverse dns entries (or
> setup correctly anyways)...Try looking into good third-party email
> filtering software.
> 
> Shawn M.
> 
> > -----Original Message-----
> > From: Darren Haun [mailto:dhaun@xxxxxxxxxxxxx]
> > Sent: Thursday, November 11, 2004 7:15 AM
> > To: [ExchangeList]
> > Subject: [exchangelist] Reverse DNS
> >
> > http://www.MSExchange.org/
> >
> > How do you set up Reverse DNS on your Exchange Server to reject
> messages
> > that don't correspond to the IP address/Reverse DNS entry.  This
> tactic is
> > usually used to block spam.
> >
> 
> 
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