How to enable green flag in emails?

Question

Domain Name System

Hello.
I have ubuntu 20.04 and ISPManager 6.

A few questions. * mysite.com - symbol.
1. I have an SSL certificate. It is for the mysite.ru mail.mysite.ru domain and subdomain, I created a mail domain for mysite.com. if I create a mail domain for mail.mysite.ru in ISPManager and when I create a mailbox there, then it looks like [email protected] In my understanding, I should create the mail domain mail.mysite.com and not mysite.com, or does it generally, in principle, not matter? But if you use mail.mysite.com, then I would like to have mailboxes like [email protected]
2. When I send letters, for example, Yandex.mail displays my messages like this:

What I did:
- I enabled OpenDKIM (exim) in the mail domain settings
- I checked the DNS records that were created automatically, here they are:
dkim._domainkey.mysite.ru.
_dmarc.mysite.ru.

What should I do to have a green flag there? Here it is, here it is:

Answer 1

Check, for example, through mail-tester.com, you may not have the same HELO and rDNS

Answer 2

Set up SPF, DKIM, DMARC, PTR.
Check the domain on the postmaster of the mail server where you send mail. You can start with postmaster.mail.ru