How to make a domain redirect with saving mail on the old domain?

Question

Mail server

Good afternoon! Made a permanent redirect 301 domain to a new domain. There are email addresses on the old domain that I would like to use for the time being. After a redirect, when sending letters to the old domain, it says "The letter was sent to a non-existent address." How to make a correct redirect while keeping old email addresses?

Answer 1

The problem was on the cPanel side. The cPanel support got involved and solved the problem.

Answer 2

After a redirect, when sending letters to the old domain, it says "The letter was sent to a non-existent address." How to make a correct redirect while keeping old email addresses?

How do you do it and on what?