How to organize mail archive storage in a corporate environment?

Question

MTA

Hello, friends!
For several days now I have been puzzling over the question of how best to organize the storage of an email archive. What is now, exim+dovecot+AD. The task is to make a certain archive so that users themselves can dig through it and pull out what they need. This archive will store all correspondence older than a year, respectively, on the mail server, letters only for the last year.
So far, a separate IMAP server only comes to mind and connect the archive as an additional box in the mail client.
Maybe you have thoughts on this matter. I would be grateful for any advice.
Thank you.