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.
Hunter - Find all the email addresses related to a domain
Symantec Email Security.cloud - Symantec Email Security.cloud provides always-on, inbound and outbound email security against malware, targeted attacks, and advanced threats
AnyMailFinder.com - Find anyone's email address
Cisco Email Security - Cisco Email Security protects against ransomware, business email compromise, spoofing, and phishing.
Norbert - Norbert is an online tool that helps you to find anyone’s corporate email address.