Over the weekend, something went nuts and built up a healthy supply of "server y unavailable: ON, server y unavailable OFF" messages. These were sent out all weekend every 10 minutes or so. They're still going out, even after bouncing the zabbix server. If I look in the Actions History, I see about 1100 messages marked as "not sent". Zabbix is slowly going through this list, and all new alert actions are getting inserted at the tail. Is there a way to flush this list?