Sets an ISO 8601 formatted timestamp of when the user was last alerted about an upcoming appointment in the calendar described by the Source to which this belongs.
If last_notified is non-%NULL, the function will validate the timestamp before setting the
last_notified property. Invalid timestamps are discarded with a runtime
warning.
Generally, this function should only be called by an alarm daemon such as evolution-alarm-notify.
| this |
an SourceAlarms |
| last_notified |
an ISO 8601 timestamp, or |