I was afraid I was going to have to keep the FUD, lies, and bogus ideology to myself.
you failed
Fortunately, decent anti-spam software won't block your mail, so this is a non-issue for most people.
MXs getting bombed from infected PCs on subscriber access network is HUGE issue for every MX on the planet, 30% - 40% of all abuse traffic is from these networks, 99+% of traffic from these networks is abuse.
And, at 1 billion spams a day, that's at least 300,000,000 E-mails a day coming from those networks. At 99+% of traffic from those networks being abuse, that's up to 3,000,000 legitimate E-mails/day being blocked.
99+% does not equal 99%, but it's close enough for Scott FUD
For every IP of a legit MTA with a PTR in subscriber style, there must be 1000 IPs with infected machines doing direct-to-MX abuse. 0.001 of subscriber IPs are legit mail servers. As small as that is, there is another fractional multiplier. And whatever the fraction is, it's decreasing as many more new, infected subscribers are increasingly populating these networks world-wide, at much higher rate any increase in legit MTAs.
In addition to the number of IPs is the msg volume. Anybody who is running a mailserver on a cable or DSL is almost always a small organization with a small volume 10's or 100's of outbound msgs per day. In comparison, an infected PC spewing abuse can send out 100's or 1000's of msgs per hour. Roughly, the volume of legit msgs vs abuse msgs is
0.001 of subscriber IPs are legit x .01 of total volume from subscriber networks = 0.00001
0.00001 of your 300,000,000 = 3000 legit msgs in 300,000,000 abusive msgs.
And any MX that adopts a policy of blocking subscriber networks by PTR can easily identify its set of legit MTAs and whitelist them.
A huge weakness of Imail/declude is that they can't block by PTR hostname.
A huge weakness of declude is that they it wastes bandwidth, by accepting ALL msgs before they can be rejected. Totally insane, when the wasted bandwidth is often 8+ times greater than the legit mail/dns bandwidth of legit traffic.
Probably over 90% of all infected mail is from these networks.
So you can block 90% of viruses and 40% of spam in exchange for blocking millions of legitimate E-mails.
Total FUD, actually total BS. You're using "%" (apples) vs "millions" (oranges) to make your bogus point, which is no point at all.
Like C/R, it is FUSSP (see http://www.rhyolite.com/anti-spam/you-might-be.html ). It works great on one machine under a given set of conditions
FUD again. Because subscriber networks are so universally infected and abusive, blocking by PTR hostname is effective for all MXs.
, but fails (a billion legitimate E-mails blocked as spam each year) if everyone does it.
FUD. Blocking by subscriber networks by PTR hostname is extremely effective and efficient.
Len
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