For a business like mine, the collateral damage is two-sided. While it hopefully is a small step to encourage the big network operators to mend their ways, it has the potential to really harm my business. "This never happens with my ISP at home" or "my competitor got this mail, why didn't I?" are phrases that I never want to hear again if I can help it.
Everybody knows there are a wide range of requirements for blocking spam, of acceptable levels of blocked legit mail.
So am I part of the problem by accepting mail from these sources?
"part of the problem" is too strong, but your sense is correct.
I believe that, if Internet mail is even recoverable from the current disaster, one step forward is that we ALL MUST raise the level of minimum credentials for every MTA presenting msgs at our MXs. If the credential are not met, reject.
An example, unfortunately not yet widely followed by other big ISPs, is AOL's initiative of insisting on a PTR, _any_ PTR. This is hardly, in 2003, an indefensible, unfair, impossibly-high requirement. But for the MX providing the numbers of my post, fully 35% of all IPs sending mail to that MX have no PTR. This is ridiculous. No server purporting to be a business server, or in any way legit, should be permitted to send mail without a PTR.
Why can a server be denied delivery to AOL on the sole criteria of being PTR-less but the same server is permitted to send to your MX?
Another requirement is the HELO hostname, which must be a fully-qualified domain name that has DNS records of type A or MX. Anything else is illegitimate and rejectable on that sole criteria.
And here's where the tactic exemplified by the subscriber filter comes in: any IP or network that repeatedly fails to meet the minimum credentials after x number of msgs or x amount of grace period, or continually demonstrates ill will (sending dozens or 100s of msgs per day to users unknown in our domains, and/or sending them from 10 or 20 IPs in the same ClassC or subnet, or sending the HELO command with Microsoft.com/aol.com/yahoo.com/etc when the PTR is not those domains or unknown, will be permanently blocked.
Somehow we need to get some true Internet movers and shakers
how about yourself? how about every Imail admin in this list?
to declare that all email servers on such-and-such a date should reject mail from all mailservers that don't have reverse DNS or have problems a, b and c.
Go Ahead, Make My Day. :)) This is exactly the tactic I think we should all implement. I have been preparing a msg that I will post here and on my IMGate list on such an implementation in the next few days.
Len
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