Correct SPF settings if the domain of the mail server and the sender are different?

Question

Domain Name System

There is a mail server mail.server.com. Through it we send letters from the box [email protected]
How, in this case, to correctly configure SPF and for which of the domains?

Answer 1

Your addresses plus all addresses of mx and a records
your ip and spf yandex records

v=spf1 ip4:136.243.82.21 ip4:136.243.82.20 include=_spf.yandex.ru ~all

Answer 2

You need to configure SPF for the domain that is used in the envelope-from, usually in the received letter this address is visible as reuturn-path. If it matches [email protected], then publish the SPF for it, but specify the IP address (or addresses) of the server
where 1.2.3.4 is the server address. You can use the construct,
but it is preferable to use IP addresses.