How important is it to make your own mail server so that it reaches gmail / yandex / mail?

Question

Mail server

About 6 years ago, you could do this: your VPS on it dovecot + exim4 -> mail relay, for example, nicru / regru, etc. -> the rest of the world.
Letters perfectly reached the recipients of gmail/yandex/mailru/yahoo - there were no problems.
Is this scheme still valid? If not, what would you advise - the letters themselves should be on their server. I found on the Internet that using mail relays is no longer good + Google has complicated the verification of letters and now when using mail relay, letters will immediately fall into spam or not reach at all.

Answer 1

To receive letters, you need to:
1. Configure DNS. MX-record, A-record of the host, in the reverse zone the corresponding PTR-record.
2. Buy a certificate for SMTP and attach it to the server. The subject name in the certificate must match the DNS hostname.
3. Go through the public blacklists and delete your IP from there, if it was there.