How can I create my own online service for corporate mail for a domain?

Question

Mail server

I want to create a service for providing corporate mail services for a domain. It looks like Yandex traffic rules, the system administrator of each of the enterprises can create mail accounts, bind aliases, but all through my mail server.
I'm looking at Zimbra, but I can't understand if they have such a function.
Please tell me how can I do this...