Either find a mail provider that helps you achieve compliance with the common terms of such providers - or do work on implementing best practices.
I recommend you use one of the many (often free) third-party test services to confirm that your PTR,TLS,SPF,DKIM,DMARC,unsubscribe-headers,.. is working and additionally use the Google-provided postmaster tools to ...
Can you provide information about what mail server you are using?
Google does mention a few steps you can do to avoid landing in spam folder or being bounced.
Assuming the fully qualified domain name (FQDN) of your mail server is vps.mydomain.com and the ip address of the server is 22.214.171.124:
Do you want to receive mails on that server? Then add a mx ...
There's no easy solution for your problem, but you can have a look at the way Mozilla Thunderbird attempts autoconfiguration of a user's email account. Details are here:
Most promising is the ISP database they maintain. This database can be queried through a special URL https://...