Continuously Emailing

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Component | Version
My libreNMS system continuously emailing for all my devices that they are down, but in reality , all are up, DNS resolving is happening, on the alert history events are clear, but emails are still sent, please advise what it might be, below are the details for the LibreNMS version

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LibreNMS | 1.57-89-ge1ede81
DB Schema | 2019_04_22_220000_update_route_table (147)
PHP | 7.2.7
MySQL | 5.6.30
RRDTool | 1.4.8
SNMP | NET-SNMP 5.7.2