Address Assignment Question

William Herrin bill at
Mon Jun 20 14:41:38 UTC 2011

On Mon, Jun 20, 2011 at 8:13 AM, Steve Richardson
<steverich.nanog at> wrote:
> We have a customer who, over the years, has amassed several small subnet
> assignments from us for their colo.  They are an email marketer.  They have
> requested these assignments in as many discontiguous netblocks as we can
> manage.  They are now asking for more addresses (a /24s worth) in even more
> discontiguous blocks.  What I'd like to know is whether there is a
> legitimate use for so many addresses in discontiguous networks besides
> spam?

Hi Steve,

Best case scenario: they're using lists from their customers who
claimed they followed proper practices when building the lists but
didn't... because nobody who farms out bulk email builds a list via
"confirmed opt in" as expected by best practices. When one of the
lists gets filtered, they want the others to be protected.

Worst case scenario they are deliberately spamming and trying to hide
under the radar by spreading it out.

> I am trying my best to give them the benefit of the doubt here,
> because they do work directly with Spamhaus to not be listed (I realize
> reasons on both sides why this could be) and searches on Google and spam
> newsgroups for their highest traffic email domains yield next to nothing,
> given the amount of email they say they send out.

Try tools like and and run through their
existing address space. When you're skirting the gray zone, Spamhaus
is generally the last one to list you. Find out what the other RBLs

> However, if they
> *are* legitimate, which certainly is possible, are discontiguous networks a
> common practice for even legit operators, as it's quite likely that even
> legit email marketers will end up being blocked because someone accidentally
> hit 'Spam' instead of 'Delete' in their AOL software?

If this was a brand new customer, I'd say hell no: they're obviously a
spammer. Since they've been with you for years and haven't tripped the
filters yet, I wouldn't be inclined to send them packing. As a
contingency to receiving the spread-out assignments, however, I would
ask them to sign a document to the effect that they only use email
lists built with confirmed opt-in with a stiff and escalating dollar
penalty clause should your abuse department receive convincing and
voluminous complaints that they didn't.

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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