Anyone else have problems emailing Cisco? (senderbase)

Tim Chown tjc at
Wed Sep 24 14:58:15 CEST 2014

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.

Anyway, thanks :)


On 24 Sep 2014, at 13:41, Andrew 👽 Yourtchenko <ayourtch at> wrote:

> Tim,
> Roger that!
> We're checking internally what's going on.
> Changing just one nibble in the host portion of the address makes
> SenderBase score "neutral", so something must be up for that
> particular /128.
> When I learn more, will ping you.
> --a
> On 9/24/14, Tim Chown <tjc at> wrote:
>> My emails to Cisco people are now bouncing.
>> It seems the cause is a poor rep on one of our MTAs:
>> The DNS reverse seems fine for
>> But the email bounce (with username deleted) says:
>> Final-Recipient: RFC822; xxxxxxxxxx at
>> Action: failed
>> Status: 5.1.1
>> Remote-MTA: DNS;
>> Diagnostic-Code: SMTP; 550 Connections from the host
>> (2001:630:d0:f102::25e), originating from SenderBase Network Owner ID: None,
>> are being rejected due to a low SenderBase Reputation Score. See
>> for more information or contact your IT support
>> team.
>> If any Cisco people are on this list, please have someone have a look. I
>> think Andrew Yourtchenko is, and he is one person with bounces.
>> Tim

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