What are some alternatives?
Barracuda Email Security Gateway - Barracuda's Email Security Gateway is a powerful antivirus filter specifically designed to identify and eliminate email-borne threats, stopping hazards before they reach the network.
WebTitan - WebTitan is an advanced DNS based web content filter and web security layer that blocks malware, ransomware and phishing attempts as well as providing web content control. Cloud and gateway versions available.
Symantec Email Security.cloud - Symantec Email Security.cloud provides always-on, inbound and outbound email security against malware, targeted attacks, and advanced threats
OneLogin - On-demand SSO, directory integration, user provisioning and more
Proofpoint Email Security and Protection - Learn about Proofpoint's email security solutions that protect organizations against threats such as email fraud, phishing, spam, bulk email, and viruses.
Webroot - Webroot delivers multi-vector protection for endpoints and networks and threat intelligence services to protect businesses and individuals in a connected world.