How to make sequential sending of letters from the mail server to the client?

Question

Mail server

Good day. There is a need to implement sequential sending of messages to a specific group of emails. The mail server is ours, the clients are connected directly. The bottom line is that, let's say five letters came in, they should be distributed among 10 clients. Details and nuances are not important yet. The main thing is that you can configure everything, or add it. I searched for Old, but apparently I didn’t search so badly, that I didn’t really find anything.
UPD. Zimbra mail server.

Answer 1

Problem solution found, RoundCube + script. Thanks to all.

Answer 2

In the server configuration, create mail routing rules so that the server knows what to do. More details can be found in the documentation .

Answer 3

Late)))
5 letters have come and all should get to 10 clients?
1. Alias. Give clients aliases to 1 postal address.
2. Zimbra has a cool "Mailing List" feature. Let the letters be sent to a special email, and from there it is sent according to the list of addresses.