What is the correct mail server configuration?

Question

SMTP

Happy New Year everyone.
I want to create a corporate box for the company.
Sometimes we will sin with news - but for subscribers (there is a collection form)
I have been looking for information on the net for a long time, but I don’t find an unequivocal answer to my question.
This is about the following:
Some servers recommend making a mail domain on the main domain, some services specifically on a subdomain .
If I put a mail server on a subdomain - helo I also introduce myself as a domain or subdomain.
And if I send a newsletter, then should I do a mailbox from a subdomain or domain?
Mail / Yandex / Google will respond better to what configuration.
Everyone says something differently - or does it not matter?

Answer 1

The mail service has its clear and strict limitations,
but in general - if you yourself do not understand and do not try to learn - contact the specialists.

Answer 2

in fact, I'm confused by such a mismatch in all configuration manuals, they
recommend host hiring hostname mailer.domain.ru
and at the same time they write "Ideally, when the server name in the header and the address of the message sender match." - at what all.
in this case recived will be mailer.domain.ru and the sender will be [email protected]

Answer 3

1. Nobody likes newsletters. But at the same time, no one will identify it as a mailing list if you send each recipient an individual letter.
2. In fact, there is no difference from where you will send the newsletter from a domain or subdomain.
3. Why they choose a subdomain for mailings - probably because mail server administrators think they can somehow reduce the impact on the main business domain (although if the same riley is used, I'm afraid this will not help much).
So, in answer to your question, where to send the newsletter from - it doesn't matter.
The main thing is to configure the service correctly, spf/dmarc/dkim/rdns -> check mail-tester.com for cleanliness of your mail and go...