Re: [Asrg] [ASRG] SMTP pull anyone?

Douglas Otis <> Fri, 28 August 2009 17:36 UTC

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Date: Fri, 28 Aug 2009 10:36:08 -0700
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Subject: Re: [Asrg] [ASRG] SMTP pull anyone?
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On 8/28/09 4:38 AM, Daniel Feenberg wrote:


> I don't doubt that many MTAs will accept IPv6 mail. What I dispute is
> the liklihood of anyone running a legitimate Internet MTA that accepts
> mail from an IPv6 only host. My reasoning is that such a host would have
> limited connectivity. There are two reasons for this. (1) Many MTA
> operators will lag in the adoption of IPv6 due to general lack of
> interest, ability or funds, so an IPv6 only MTA will have no access to
> many MTAs, much worse even than MTAs operating at dial-up addresses
> currently have. (2) Anyone operating an MTA on IPv6 will have to do
> without the single most effective anti-spam technique we have, the
> DNSBL. This will cause many operators with the resources to add IPv6 to
> hesitate to do so.
> Given either of these two reasons, few or no MTAs will run IPv6 only,
> which obviates the need for IPv6 entirely.

One of the significant changes we needed to make in our service when 
becoming more popular in Asia's Pacific Rim, was to provide setting that 
precluded other regions by default.  This desire might not be 
xenophobic, but based rationale interests.  When large portions of a 
country's connectivity is IPv6, having preferences for IPv6 seems 
logical.  The question you might consider would be whether those in IPv6 
predominate regions even wish to accept IPv4 connections from areas 
blighted with spam in languages foreign.

> Of course, some operators can do without DNSBLs, and they can easily
> operate dual-stack. There is no practical way they can drop IPv4, nor
> will they ever be able to do so.

Be a bit cautious about considering this a general statement.

> So, how much mail came from IPv6-only hosts? And what was the percentage
> of spam?

This type of measure will never uncover the amount of region specific 
exclusions.  You might be surprised to find IPv4 is not always king.