Per default, Dovecot sends a "I'm still here" notification to every client that has an open connection with Dovecot to get mails as quickly as possible without manually polling it (IMAP PUSH). This notification is controlled by the setting [`imap_idle_notify_interval`](https://wiki.dovecot.org/Timeouts), which defaults to 2 minutes.
A short interval results in the client getting a lot of messages for this connection, which is bad for mobile devices, because every time the device receives this message, the mailing app has to wake up. This can result in unnecessary battery drain.
This isn't a default setting in mailcow because we don't know how this setting changes the behavior of other clients. Be careful if you change this and monitor different behavior.