Be sure to have a PTR record in the DNS zone of whomever owns your IP address. I have DKIM, SPF and DMARC setup, but my mails were getting sent to spam before rDNS was configured correctly.

More to the point, I discovered this by reading Google's postmaster/bulk mail guidelines. All the other major email providers have similar guidelines, so definitely consult those as a first reference if you are having problems.

There is no mail conspiracy. As always, the problem is DNS.