Hunter - Find all the email addresses related to a domain
Targeted.io - Test your email designs across 30+ clients before you send'm
Snov.io - More leads. More sales. More revenue.
Really Good Emails - A large collection of good product email design.
Apollo.io - Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.
Stamplia - High converting and beautifully designed email templates