>On Tue, Mar 14, 2017 at 3:38 AM, Philip Homburg <pch-ietf-6@xxxxxxxxxxxxxx> >wrote: > >> >> In my experience, essentially no mail gets lost if you leave out SPF, DKIM, >> DMARC. The only exception is gmail that occasionally rejects e-mail. >> > >"no mail gets lost" != "gmail occasionally rejects my mail" What I meant to write is that when I take all e-mail targets that I send e-mail to, leaving out gmail, then sending mail without SPF, DKIM, DMARC works just fine. Gmail is an exception because it seems that gmail is broken if you deliver mail without SPF, etc. over IPv6 to gmail. That's unique to gmail. So if your outgoing mail doesn't have SPF, etc. and you do have IPv6, then you have to think about what to do with gmail. In any case, that's my experience. In some sense it is amazing how reliable e-mail is. E-mail seems to be reliable enough that gmail rejecting the occasional e-mail immediately makes it the most unreliable e-mail provider (for my e-mail). That's also an amazing success story. >> In the context of IPv6 we now have an additional problem. Sites that have >> filters that are more strict for IPv6 than for IPv4. The obvious very >> quick workaround for many mail admins is to avoid delivering mail over >> IPv6. >> Of course, that just increases the SPAM/HAM ratio, justifying more >> draconian >> measures. Which in the end will just kill IPv6 as a transport for e-mail. > >Do you imagine that you may be making different choices than others? Imagine that some will be making different chocies than me, yes. >There are plenty of senders, in fact the vast majority by volume, who are >perfectly fine with authenticating their mail. And many of them send over >IPv6. This may be a speed bump, but it is not the death of IPv6 for email >transport. It is likely that a few big providers together will make up the vast majority of e-mail volume. However, gmail (or in fact any I send mail to) has not made SPF, etc. mandatory. So if gmail would make DMARC mandatory for IPv4, that would signal something. Maybe gmail can publish some graphs, contrasting the percentage of mail that arrives over IPv6 to IPv6 adoption for other google services?