On 23/08/2014 11:16, 🔓Dan Wing wrote: > On Aug 22, 2014, at 7:42 AM, Matthew Huff <[email protected]> wrote: > >> Currently it is not feasible to do ipv6 reputation filtering. IPv4 >> reputation filtering is a big part of most anti-spam engines, so without it, >> SPF / DKIM of domain reputation is the best alternative. >> >> BTW, we have had to remove all IPv6 from our mail gateways due to the large >> number of Exchange SBS with broken isatap/6to4 tunnels causing mail to >> blackhole. > > MTU issue?
I can't speak for Teredo, but for 6to4 there is a whole list of possible issues ( http://tools.ietf.org/html/rfc6343 ). PMTUD failure and/or MSS negotiation failure are on the list, and so is reverse DNS failure. Brian > > -d > > >> These have been at small web based retailers which don't have hosted email. >> After the third incident, we yanked our IPv6 from our MX/gateways. >> >> >> >> ---- >> Matthew Huff | 1 Manhattanville Rd >> Director of Operations | Purchase, NY 10577 >> OTA Management LLC | Phone: 914-460-4039 >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Nick >> Hilliard >> Sent: Friday, August 22, 2014 10:25 AM >> To: Lorenzo Colitti; Laurent GUERBY >> Cc: IPv6 Ops list >> Subject: Re: SMTP over IPv6 : gmail classifying nearly all IPv6 mail as spam >> since 20140818 >> >> On 22/08/2014 15:16, Lorenzo Colitti wrote: >>> Are you following the "Additional guidelines for IPv6" section of >>> https://support.google.com/mail/answer/81126 ? >> Lorenzo, >> >> it looks like Google is trying to enforce SPF / DKIM on ipv6 connections >> where there is no similar requirement for ipv4. Is there a particular >> reason for this? It's causing a lot of breakage. >> >> Nick >> > >
