Qualys - Qualys helps your business automate the full spectrum of auditing, compliance and protection of your IT systems and web applications.
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.
Trend Micro Deep Security - Excellent hybrid cloud security doesn't require your business to sacrifice operational performance. Trend Micro lets you keep business moving securely.
dmarcian - Safeguard your email from abuse
Google Cloud Platform Security Overview - Cloud Workload Protection Platforms
Hornetsecurity - Hornetsecurity offers you comprehensive, integrated managed e-mail security services.