[cpncrunch]

Did you fill in the delivery problem form?

https://support.google.com/mail/contact/msgdelivery?vid=0-35...

I had a problem with ipv6 myself with gmail, but the problem was that I just didn't have ipv6 fully set up on my server, so either SPF or reverse DNS wasn't working or something like that. I think I just configured sendmail to only use ipv4 and that solved the gmail issue.

[saltybytes]

"I think I just configured sendmail to only use ipv4 and that solved the gmail issue."

This was my experience, too. I took this advice [1] configuring postfix and Gmail started to accept my emails.

[1] https://christian.skala.me/blog/gmail-why-are-you-doing-this...

[cpncrunch]

My issue was that I wasn't very familiar with ipv6, and my ISP (OVH) apparently gave my server a range of about 256 ipv6 addresses, and I didn't really know how to properly set up reverse DNS and SPF. After spending a day or two getting nowhere, I just decided to turn off ipv6 completely for the server.