How to handle custom .Spam imap folders on the server?

Question

Email

Good day!
There is a mail server where mail is stored in the Maildir format. Some users mark emails as spam and don't want to receive them anymore. These letters quite logically end up in the .Spam folder in the user's folder on the server. Based on such folders, I need custom blacklists. Has anyone used something similar? Share your experience
Thank you!