Why do Hotmail & Gmail mark all emails as spam for no clear reason?

Been testing for DKIM, SPF, DMRC and all of them are valid. Proven over several online tools. mail-tester.com gave 8.8 points.

Server is not blacklisted anywhere, so far I checked.

But no matter what content (html or plaintext) I send gmail delivers it to recipient's spambox and hotmail not even accepting it.

I'm desperately no idea why this happens. Please could you give any suggestion.

My server runs exim with dovecot and opendkim.

Following are the headers from latest sent (marked as spam) email

As far as I can see, the reverse DNS PTR from your server's IP does not forward resolve to the same IP address (FCrDNS) - our mail system would reject because of this as the rDNS looks fake.

You should also use a third level host name instead of the second level domain name, e.g. mail.domain.tld instead of domain.tld since your 2nd level domain is likely to resolve to your web server.