On Wed, Jan 09, 2013 at 09:27:17PM -0600, Chris Boyd wrote:
We're small shop, but our policy is not to accept email from addresses without PTRs. And we have a long list of pool/dhcp/dyn/resnet PTRs we don't accept mail from as well.
This is (and has been) a best practice for most of a decade, ever since the rise of the zombies. Real mail servers have matching A and PTR records, and real (i.e., non-generic) FQDN hostnames. They also HELO/EHLO with real, non-generic FQDN hostnames that resolve, and which (preferably) match that in the A record. Everything else is at best suspect and probably either (a) a zombie or (b) incompetently run. Thus -- and these are examples seen in a local spamtrap in the last few hours -- none of these should be permitted to even *attempt* to deliver mail to real live addresses: 2.132.135.33 (no rdns) 37.44.121.227 (no rdns) 41.97.154.184 (no rdns) 41.191.104.24 (no rdns) 46.177.235.253 ppp046177235253.access.hol.gr 60.254.50.150 50.254.60.150.hathway.com 64.25.225.52 (no rdns) 74.7.101.50 (no rdns) 77.126.116.112 (no rdns) 79.180.105.90 bzq-79-180-105-90.red.bezeqint.net 80.232.221.197 (no rdns) 81.248.60.11 lcayenne-151-5-11.w81-248.abo.wanadoo.fr 85.30.103.215 (no rdns) 88.77.212.175 dslb-088-077-212-175.pools.arcor-ip.net 89.223.2.149 ip-149.2.223.89.net.unnet.ru 93.86.110.126 93-86-110-126.dynamic.isp.telekom.rs 95.140.197.66 host-95-140-197-66.customers.adc.am 110.49.235.132 (no rdns) 117.6.200.103 (no rdns) 117.212.210.190 (no rdns) 120.61.90.56 triband-mum-120.61.90.56.mtnl.net.in 122.163.226.123 abts-north-dynamic-123.226.163.122.airtelbroadband.in 122.166.232.127 abts-kk-static-127.232.166.122.airtelbroadband.in 123.24.97.69 dynamic.vdc.vn 123.24.198.246 (no rdns) 178.126.109.101 (no rdns) 190.66.167.111 (no rdns) 195.128.253.152 ip253-152.dl.uz.ua 200.56.5.180 200-56-5-180.dynamic.axtel.net 200.67.199.254 dsl-200-67-199-254-sta.prod-empresarial.com.mx 201.230.49.12 client-201.230.49.12.speedy.net.pe 206.55.180.8 (no rdns) 213.175.137.146 (no rdns) 220.227.74.69 (no rdns) 222.124.11.26 26.subnet222-124-11.astinet.telkom.net.id 222.253.178.173 localhost ---rsk