How to send mail to another MX?

Question

PHP

If I knew how to better formulate the question, I would have found the answer myself ;( so don’t kick it.
There are two mail servers
mx1 Yandex
mx2 local
on the servers there is a site, DKIM DMARC, etc. everything is configured taking into account both servers and works correctly.
until the moment when I on a local web server I'm trying to send mail to myself, in which case postfix simply shifts it from outgoing to incoming and does not take a steam bath, but I need it to send mail for a domain known to it, in the same way as for any other domain
. I need the letter [email protected] to come to a Yandex account that also holds the same zone.

Answer 1

CyberHost is right, you can still severely limit the number of digits:
https://regex101.com/r/mV3wA0/1

Answer 2

Directive mydestinationin postfix settings.
www.postfix.org/BASIC_CONFIGURATION_README.html#my...