North American Network Operators Group
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Re: On-going Internet Emergency and Domain Names

  • From: Andy Davidson
  • Date: Tue Apr 03 03:58:47 2007


On 2 Apr 2007, at 21:21, Lasher, Donn wrote:

Rather, I thought a lot more providers would actually be blocking outbound
25 except to their SMTP servers. Just brought up a new mail server for a
friend; moved an old (14+ year) domain.. I was amazed at the number of
connections from rr.com, comcast.net, cox.net, verizon, etc etc etc
obviously not "official" mail servers. I'm actually tempted to start
blocking anything that doesn't say "mail." in it somewhere.. :)

Lots of people do use the 'came from some consumer isp dynamic range' as a reason to block mail by using RBLs which list the entire dial-up/ dynamic ranges of ISPs they know about[0], so if you wan to have a go at doing that, don't just drop any inbound mail from mtas which don't have reverse dns set to mail.something. At least, not without telling your customers that they can outsource their mail to my company ;-)

[0] - e.g. http://mail-abuse.org/dul/