Mimecast Gateway - Mimecast Gateway is a SaaS-based email security solution that uses sophisticated, multi-layered detection engines and intelligence to protect email data and employees from malware, spam, advanced threats and zero-day attacks.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
dmarcian - Safeguard your email from abuse
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Hornetsecurity - Hornetsecurity offers you comprehensive, integrated managed e-mail security services.
Prometheus - An open-source systems monitoring and alerting toolkit.