How to wish you hadn't forced ipv6 adoption (was "How to force rapid ipv6 adoption")

[johnl at iecc.com (John Levine)]

>Using the link-level address to distinguish between good and bad email
>content was always daunting at best. Thanks for pointing out that this
>flawed behaviour must cease.

I don't know anyone who does that.  But I know a lot of people who use
both IPv4 and IPv6 addresses to distinguish among "has sent legit
mail", "is a spambot", and "no history".  Those are handy when mixed
into the usual multi-factor spam filtering.  Outright blocking on
conservative lists of spambots like the CBL (now XBL) works well, too.

R's,
John