How to check the recipient on different mail servers?

Question

Mail server

Hello everyone, the situation is as follows:
We bought a mail service on Migadu and have on-premise iRedAdmin. Registered all DNS records, everything works, only there is one BUT.
mx Migadu servers have a higher priority, and when I send a letter to a mailbox that is only on iRedAdmin, an outlul arrives. Accordingly, the mirror situation is when I put the priority of my server higher. How to make sure that the check goes on both services and the system does not beat outloop?

Maybe there is some kind of service or it can be raised at home?

Answer 1

you cannot receive external mail for different recipients of the same domain on different servers, because MX is written for the domain as a whole. You can
1. Receive all letters for all recipients on your onpremise server, from there some of the letters are redirected to an external one (and/or vice versa).
2. Make a separate subdomain for another server and use it
. In English it is called bounce.