I run an email security/monitoring business [0], and we hear this issue with Gmail a lot, in fact: we have been bitten by it as well during the early days.
The problem at hand is that it is really hard to debug situations like this. Google won't tell you why a particular email is blocked, because that information will be immediately exploited by spammers.
We build our software suite because we found that mistakes in email configuration are easy to make and really hard to identify.
I did a quick scan of rafa.eu.org and found the following:
- SPF is setup [1] with a neutral 'all' mechanism, which basically disables SPF for this domain. Hence, DMARC will set SPF as 'pass' even though SPF did nothing here to help the spam algorithm to assess the sender.
- A DMARC record exists and has a valid syntax [2], but the proposition (p value) is set to 'none', which basically disables DMARC altogether. It will enable reporting, but nothing more than that.
- I don't know you DKIM selector, so I can't assess that, but make sure the DKIM signature address is aligned (using the same domain name).
- The TLS configuration of your email server uses a self-signed certificate and is very much outdated (it offers SSLv3 and RC4 ciphers). I used testlssh.sh [3] to check this.
So yes, you technically did setup TLS, SPF and DMARC, but in all 3 you have configuration errors. Running a mail server in 2019 requires a bit more work and maintenance than it used to be 10 years ago, but the reason is spammers, not Google. Remember: it is in Google's best interest to have as few false positives, as it ultimately benefits the users. It's just really frustrating that it is hard to figure out why Google is marking your email as spam.
[0] https://www.mailhardener.com
[1] https://www.mailhardener.com/tools/spf-validator?domain=rafa...
[2] https://www.mailhardener.com/tools/dmarc-validator?domain=ra...
[3] https://testssl.sh/