Anyone else have problems emailing Cisco? (senderbase)

Bjørn Mork bjorn at
Wed Sep 24 15:22:43 CEST 2014

Tim Chown <tjc at> writes:

> The IPv4 rep for the same MTA is Good.
> Would be interesting to see why the IPv6 rep would be different. Spam from that MTA would presumably go out over whichever protocol was available.  Perhaps because there’s a much smaller sample size on IPv6 (maybe 3% of our outbound is IPv6 last time I looked) it’s more susceptible to a small amount of email that’s deemed spam.

It might be related to the second bullet point here:

  "Your IP exhibits DNS patterns that indicate compromise by a
  SpamBot. Make sure your DNS is configured according to the protocol
  for RFC2821, section

A gold star to anyone who is able to explain what they mean by that,
ignoring the fact that RFC2821 was obsoleted by RFC5321 more than 5
years ago.


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