How to store/display all mail correspondence?

Question

Django

The task is to store all the correspondence of one mail and then display it on the front-end. Mail can be different, gmail or domain. So far I have no idea how to do it.
Is it really necessary to do this through gmail ? let's say I can receive all new emails, after the user has read a certain message, I have to tell gmail - y that the user has read this message and wait for a response from him then send this response to the front-end. Extra actions are obtained.
Or I see it differently, buy a separate server, deploy a certain mail package there, then send it to another after receiving a message ... Although no, the situation with gmail is repeated.
In general, I have no idea how and through what to do it.

Answer 1

on the local server is any mail server.
it also has a mail collector, for example, the classic fetchmail. he collects mail from Google and others and puts it in the local one.
on local you already do anything with mail.
for access to mail on the local server you put dovecot.