Exim Relay and multiple domains: how to make it work?

Question

Exim

Good afternoon. There is a web server on which sites are spinning, each on its own domain. Because I don't want unnecessary work with the contents of my mail server, I decided to use the Yandex traffic rules mail service. (Because all domains use NS servers from the same company, there were no problems). I send mail through SMTP with authorization. Configured for one domain - everything works fine. But at the moment I already have 3 domains of unrelated projects, so I want the mail (generated by the CMS) to go for each domain through my mail account.
Those. if the mail has from:[email protected] then send via smtp.yandex.ru:[email protected]:password and similarly for example2, .... N
Immediately ssmtp was replaced by exim. On this, everything stood up.
It was not possible to find ready-made (or close to such) solutions on the Internet. A colleague advised me to dig in the direction of writing rules for exim transport. But since I have never dealt with the maintenance of mail servers before, I didn’t really master it.
Help good people.

Answer 1

For exim4, hubbed_hosts can be used .
After that, we write the rules in the file:

# Для доменов в ПДД Яндекса:
yandex-mail.domains: mx.yandex.ru