Hi!

We are setting up an Nginx mail proxy to seamless migrate from Cyrus to Dovecot. We used this documentation to implement it: https://docs.nginx.com/nginx/admin-guide/mail-proxy/mail-proxy/
Currently, we are only using Cyrus behind the proxy but are encountering an issue with the number of IMAP connections from Nginx to Cyrus because they are left open until Nginx is restarted.

We are wondering now if we can set a keepalive timeout for the upstream connections. For HTTP upstreams there is the `keepalive` setting but I was not able to locate a similar setting for mail.

Does anyone know how to adjust this to not have thousands of open IMAP and POP3 connections?

Thanks for any hint on that.

Best regards!