Gmail refuse the 70% of emails since 3 months ago

Since 3 months ago, Gmail it’s starting to refuse the 70% of emails sended through my domain, I check de DKIM, SPF and DNS configs but I didn’t found the issue.

The DNS config of website that are trying to send emails and the DNS of domain that have the mail server don’t have proxied any email related record and A record for email server aren’t proxied too (I try to post the DNS config images but as new in the forum can’t include embeed content or links)

The email pass DKIM and SPF checks, send emails without problems, but gmail refuse the 70% of their with this message:

This is the mail system at host mail .mitsuhakitsune .com.

I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

               The mail system

<[REDACTED]@gmail.com>: host gmail-smtp-in .l .google .com[2a00:1450:400c:c1b::1b]
said: 550-5.7.25 [2001:41d0:8:d44d::1] The IP address sending this message
does not 550-5.7.25 have a PTR record setup, or the corresponding forward
DNS entry does 550-5.7.25 not point to the sending IP. As a policy, Gmail
does not accept 550-5.7.25 messages from IPs with missing PTR records.
Please visit 550-5.7.25
ht tps://support.google .com/mail/answer/81126#ip-practices for more 550
5.7.25 information. ba26-20020a0560001c1a00b002207a5b383esi4545116wrb.387 -
gsmtp (in reply to end of DATA command)

I check the reverse DNS with the server IP too and resolve on mail. mitsuhakitsune. com without problems, so I don’t know why gmail still refusing the messages, and all work fine for a few years, this error start since 3 months ago.

When some email fail, if I retry a few times the email work and gmail don’t refuse it.

Someone know how to fix this issue?

Thanks for read, greetings.

Ok, I managed to solve this (I guess, I waiting for DNS propagation), the problem of this error isn’t related with Cloudflare.

After check with detail the email of bounce back from gmail, I see that make reference to IPv6, checking my reverse PTR for my IP I see that appear as blank.

To solve this, I create AAAA record pointing to the same subdomain of my email server and I setup on my hosting provider the IPv6 reverse PTR.

I’m so sorry for disturb with this, on first time I think that are related with my DNS, but no.

Greetings.

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