How to set up mail for a domain so that letters are processed on hosting and mail.ru servers?

Question

Email

Good day!
Task: (as I understood it) Set up mail on the domain (like [email protected]). Letters should be sent to mailboxes located on the hosting of the site (dedicated server) and on the mail.ru mail server.
Comment: At the moment, mail comes to all mailboxes on the hosting and only 1 on mail.ru. At the same time, MX records are not specified for the domain (as I understand it, the domain itself @ MX 0 @ is specified by default).
Question: This is my first time dealing with mail settings. How, exactly, to make this scheme work?
PS Also, useful links to information on this subject are welcome.

Answer 1

The easiest way is to simply log in to mail.ru with a box from the hosting, while Mail.Ru mail will actually work as a web client to the mailbox from the hosting, perform all the necessary synchronization.

Answer 2

https://help.mail.ru/biz/domain/add
Well, in DNS it is desirable to be able to understand

Answer 3

Do you need to STORED messages both there and there, double "backup"?
Is picking up by imap not an option?