Hunter - Find all the email addresses related to a domain
MailStore - MailStore Home - A 100% free single-private-user desktop solution
Apollo.io - Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.
MailSteward - MailSteward : The Ultimate E-mail Manager for Mac OS X
Icypeas - This email finder has the capacity to bypass catch-alls
Gmvault - Backup the emails in your Gmail account.