Re: The block message is 521 DNSRBL: Blocked for abuse

[Bill Woodcock <woody () pch net>]

On Sep 18, 2013, at 9:07 AM, NANOG <NANOG () abcsupply com> wrote:
> We recently purchased new IP addresses from ARIN

No, actually, you didn't.  You were assigned the use of the addresses, based on need.  Just as a radio station does not 
"purchase" spectrum.

https://www.arin.net/policy/nrpm.html#four3

> Our mail server IP address is 74.112.99.25.  Is it possible they are blocking us based on old information from the 
> previous IP address block owner?

Quite likely, yes.

John LeCoque's suggestions seemed quite sound:

> I would say the first step is to find an immediate workaround for your end
> users - maybe bring up a VM on AWS or some other cloud provider to use as
> an SMTP relay while you work out the blacklist issue. If you run into
> blacklist issues after that, you may want to take a very close look at your
> outbound mailflow to make sure your organization isn't sending out messages
> that could be categorized as spam.

                                -Bill

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