Getting my emails from 2 different private servers

I was trying to get all my emails from 2 different private servers and found it does not work.

I have about 60 emails of which about 30 are very active and some are reserved in case of improper unwanted emails like junk, spam etc'. All these emails are under 2 main domains at one private server.

I also have another server with 3 different domains, and only about 10 email addresses, but the only way to get these to my computer is by rerouting the emails FORWARDING them to my main server's email system.

I want to add emails to my second (newer)server and be able to use all emails at both servers as one. Is this possible?

I did not set my 60 emails as individual emails, which seem to be the automatic way Apple creates them.