Email gets sent to gmail junk

[johnny09]

What still needs to be done, to get mail in inbox, not spam?
Also other mail servers get the mail in junk. 

My mail server is a subdomain, like a.domain.com, checked all ssl, valid

[overseer]

Use Google's Postmaster Tools:
https://gmail.com/postmaster/
Getting started guide:
https://support.google.com/mail/answer/9981691?hl=en

Do you have valid a rDNS / PTR record for your server, set up by your provider? It's absolutely critical for mail delivery.

[johnny09]

Needed some time to resync DNS, now it sends correct, no junk