theHarvester
theHarvester is a simple to use, yet powerful tool designed to be used during the reconnaissance stage of a red team assessment or penetration test.
It performs open source intelligence (OSINT) gathering to help determine a domain’s external threat landscape. The tool gathers names, emails, IPs, subdomains, and URLs by using multiple public resources.
# Search emails based on example.com domain
theHarvester -d example.com -b google,linkedin