Scott, Wow, I don't know what type of subscriber network rules that you had set up, but I'm guessing that they were a lot different than mine. I don't know the exact rules that Len uses, but am assuming that his set up is a lot closer to mine than yours is/was. I have mostly relied upon DNSRBL lists of subscriber networks and DUNs in the past, and have never had a single complaint about legitimate mail being blocked or deleted using this as a criteria. Blocking these Ips blocks and addresses has always been effective for us, and I'm sure that most of the major ISPs are also using similar criteria.
As far as whether or not mail gets through using "Scott's" weighting system, it all depends upon how an admin has Declude or other rules tweaked. You are always walking a tightrope between allowing spam to pass through unscathed and completely deleting an e-mail when you rely upon a weighting system for mail deletion. Unfortunately, it's an all or nothing proposition. At least with rejection there is NEVER a chance of mail getting totally deleted, so long as there is a valid return address. Obviously, (to me at least) both methodologies have their place and their own merits. In actual practice, both your numbers and Len's numbers seem skewed at opposite ends of the spectrum, insofar as what amount of traffic that comes from ADSL connections. Strangely enough, my numbers seem to fall right in-between both of yours. Go figure. With the price of broadband decreasing as it is though, I would tend to think that more and more businesses will be able to afford T1 service in the future and more and more residential customers (and zombies) will be adding to the ADSL numbers. William Van Hefner Network Administrator Vantek Communications, Inc. > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Scott Perry > Sent: Thursday, March 24, 2005 7:34 AM > To: [email protected] > Subject: RE: [IMail Forum] reverse DNS > > > > >Yes, it is possible to have a "legitimate" mail server set up on an > >ADSL line with a subscriber network RDNS. It is also theoretically > >possible to host a "legitimate" mail server on a dial-up > connection, on > >an open proxy, on a server with an open relay or on an IP range in > >China that has been blacklisted by every single DNSRBL in > the universe. > >There are all kinds of remote possibilities. I draw the line when > >99.9%+ of the traffic is spam. > > When I last checked, a test showed that about 10%-15% of > legitimate E-mail > was coming from IPs that would have been blocked by a > "subscriber network" > test. That was perhaps a year or two ago, however, so the > numbers may have > changed. > > >At least with Imgate the odd legitimate sender receives > notice of the > >delivery failure, unlike with Scott's weighting system. > > But with "Scott's weighting system", the E-mail goes through. > > So you're comparing bouncing a legitimate E-mail with it being > delivered. I know which I would pick. > > >Anyone who goes the cheap route and routes all of their e-mail via a > >single MX on an ADSL connection without bothering to > configure RDNS is > >truly getting what they pay for. > > It isn't always that easy. In my case, the mailserver was in > a physical > location where switching from a business-class static IP > without vanity > reverse DNS to one with vanity reverse DNS would have cost > 10x the money. > > > If a company can't justify the money to spend on > >at least getting a dedicated SDSL circuit or fractional T1, > then they > >really need to rethink their IT strategy. > > That's the thinking that caused the dot com crash -- "Let's > spend $1,000 a > month instead of $100 a month so we can subsidize poor > anti-spam software." :) > > All I keep hearing is the same thing over and over -- "This > test blocks a > lot of spam." Now that is great, but good anti-spam software > can block > just as much spam while allowing more legitimate E-mail through. > -Scott > > > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html > List Archive: > http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ > Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/ > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
