While connecting to OUTBOUND google smtp, POSTFIX does not default to IPV4 anymore
if you have
smtp_address_preference = ipv4
in main.cf.
Gmail Google must have done something to force IPV6 when receiving mail from IPV6 capable servers. Overriding the postfix preference.
Thus, it is highly likely they will treat your IPV6 mail as bulk.
The only remedy for now is to set
inet_protocols = ipv4
and not accept INBOUND IPV6.
Has anybody noticed this as well?
Interesting finding. How did you find this out? Have you been able to replicate this elsewhere or with other email providers? If this turns out to be an issue, maybe a pull request to modify main.cf would be in order.
I did replicate this on another reserve domain. It seems to be the case if they mark you as a unsolicited mail sender and then they seem to have a rule to always default to IPV6 if you are running a dual stack instance.
They are just a pain in the… with their overzealous filtering. They made email messaging undesirable.
Have you actually experienced any deliverability issues after this change? I don’t want to defend Google or anything, but in my experience, if you have a PTR record, SPF, DKIM and DMARC, sending emails to Google works just fine.
However, I can think of one reason why their preference for IPv6 might cause problems: The reputation of IPv6 addresses is not very well established yet, and many IPv6 addresses probably have no reputation at all, which might be worse than being on some less relevant spam lists.
Yes my messages now bounce. I am registered on their Postmaster tools and their new dashboard says I fail SPF, from Header DMARC and Encryption. See screenshot. This is simply not true. It seems that if they manually put you on their bounce list the new dashboard shows you fail some requirements. I am not a bulk sender. Something is wrong with their filtering or my IPs have been marked by them for erratic behavior. Also I am not listed on any of the RBL lists.
