We try to keep our rDNS as accurate as possible. But in Germany there
are a lot of ISPs that think rDNS is kinda obsolete and nobody cares
anyway. So all they come up with is - like in most of
North-America and
the rest of the world - they use some fumbled IP address as
name in hex, arabic and some also in latin numbers like
The fact that the rDNS is in the state it is in is probably
symptomatic of the fact it was never given a clear and useful
purpose.
Give the rDNS a clear and useful purpose and it is likely that
it will be managed in a more reliable fashion.
One nit. The big weakness I see in MTAMARK is that the idea
is proscriptive, these IP addresses are not allowed to send email.
I think that is completely inappropriate. Don't tell the
receiver what to do, don't even try. Just give tell the facts
and let others make what use of them they may.
If ISPs want to disable SMTP from an address they should simply
block port 25. The point of MTAMARK is that this is not an
appropriate response. If someone does not want to receive email
from residential DSL the solution is NOT to stop all email
access from residential DSL.
If an ISP does not want to be held responsible for the email
comming from an IP address then just make a note of the fact
and recipients will look for other ways of holding them
accountable.
Phill