Poll on SMTP over IPv6 Usage

Gert Doering gert at space.net
Wed Feb 19 10:54:14 CET 2014


On Wed, Feb 19, 2014 at 02:45:33PM +1000, Noel Butler wrote:
> We block only by IP from whatever spam source is used (4, or 6), and
> rbldnsd handles ipv6 nicely (albeit in /64's - fair enough too, since
> most end users get that, typically), so your MTA's query would get a
> response from your DNSBL if it has an entry. 

Blocking by /64 by default is likely to get collateral damage.  Enough
people do shared subnets with multiple customers in the same /64 - while
I won't recommend it, it is *done*, and blocking the whole /64 because
you have seen SPAM from a single IP out of it is hurting the wrong

And yes, I've seen that in the wild, Ironport reputation for a very
well-behaved machine going down the drain because of "bad neighbourhood".

Gert Doering
        -- NetMaster
have you enabled IPv6 on something today...?

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