ZM_OPT_MESSAGE
In ZoneMinder you can create event filters that specify whether events that match certain criteria should have their details sent to you at a designated short message email address. This will allow you to be notified of events as soon as they occur. This option specifies whether this functionality should be available. The email created by this option will be brief and is intended to be sent to an SMS gateway or a minimal mail reader such as a mobile device or phone rather than a regular email reader.