How to organize a domain change, with the preservation of postal addresses and letters, if mail is used for the domain from Yandex?

Question

Yandex

There was an old domain, long. Got a new short. There are 5 boxes on the old one, each contains many letters and contacts.
What is the best way to transfer all this goodness to a new address if the mail is done through https://pdd.yandex.ru ?

Answer 1

1) Do not delete the old domain, renew, continue to keep it on pdd.yandex.ru
2) Transfer the site to the new domain if it exists and create new mailboxes
3) Set up forwarding from old mailboxes to new ones
4) Reply from new mailboxes, well, contacts , change business cards everywhere
5) After N years, when the data on contracts becomes obsolete and only spam is pouring onto old mailboxes, turn off the old domain