On 6/8/2006 12:05 AM, Greg Allen wrote:
However, the ISP dynamic address tests *do* belong in the MTA RBL
checks. The fraction of legitimate emails received from dynamic-IP
hosts is vanishingly small compared to the tens or hundreds of
thousands of compromised Windows boxen spewing spam and viruses...
Sorry to poke in on the thread, but I disagree.
Most small start-up businesses buy business class DSL these days with 1-5
fixed IP addresses. They often have small firewalls, anti-virus, most
everything they should have. They probably don't have a full time IT staff.
There are a lot of small businesses on these legitimate business class DSL
lines with fixed IP addresses (which they pay extra for) who are very
frequently incorrectly listed as "dynamic" IP addresses. The vast majority
of these small companies are NOT spammers.
Some of those small businesses aren't really all that small either.
There are a number of ~500 employee companies around here that have the
same problem. Some even with T1s (probably quietly provisioned over
DSL) that have IPs smack in the middle of static business DSL ranges
that are listed in SORBS' dynamic list.
If you are a system admin and you flat-out reject email that shows on
various error ridden "dial-up" lists as "dynamic" IP address for a company,
other than your own, you should be fired IMO.
Likewise, if you're a system admin that is aware that they are in such
dynamic lists and can't get out of them, you're asking for trouble not
smart hosting your mail through a (RBL list-wise) cleaner relay.
I know that in the automotive industry there are a lot of tier 1
suppliers and a number of MXes at a couple auto manufacturers that
reject on SORBS dynamic listings (of truly static space). Having mail
blocked, or worse silently discarded or unread, could easily cost you a
LOT of revenue. Having this happen when it's avoidable on your own part
is inexcusable, no matter how annoying it is that you can't send mail
directly from IP space that you are paying to do so with.
Daryl
