This module sends -- MARK --
to the log once per minute.
This may be useful to give a sense of how busy the server is or see that
logging and timers are still working.
With the plugin installer in Prosody 0.12 you can use:
sudo prosodyctl install --server=https://modules.prosody.im/rocks/ mod_log_mark
For earlier versions see the documentation for installing 3rd party modules