Matt Fretwell wrote:
Brian Read wrote:
Block all mails from dynamic IP. They are 99,99% spam.No they aren't that "rule" causes quite a few of my customers a headache, as the (linux) mailserver I often install sends the email direct, irrespective of whether there Ip is "dynamic" or "static". Some
ISPs charge an arm and a leg for static IPs.
[...] This bumph about people shouldn't be allowed to run a direct MTA to MTA setup unless they have static IP's is nonsense. One might even say that it is MTA (elitism|snobbery). There are plenty of legitimate MTA setups running on dynamic IP's. [...] What really does amaze me though, is that these are generally the admins who will turn around and say, 'Don't block (variable), you will lose too much legitimate mail'. Where is the logic in that? They will allow a crappily configured multinational corporation or ISP to connect, yet not give dynamics the slightest chance to prove their reliability.
I don't think it's a matter of reliability... it's more an issue of accountability and traceability. How can one trace back to a dynamically IP'ed MTA when it's dynamic? DynDNS doesn't prove itself in the majority of cases, or isn't even used. Some of these are even worse because the mail is coming from a NAT'ed host from behind a dyn IP firewall, which won't even allow return messages -- and I suspect this is extremely common. Kind of like an inverse roach motel for email.
I don't disagree that there may well be many people running wholesome MTAs on dynamic IP's that suffer for the rest. But it's that rest we're all concerned with. I honestly wonder whether an authorization framework such as SPF would be the salvation of such setups... permitting them to prove themselves worthy without the need for static IP addresses.
But until that time comes, any host who appears to lie about it's identity by giving a host name that doesn't match it's visible IP address is getting the door slammed in it's face by my MTA.
YMMV.
Bill
Matt
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