GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!

Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI

Trumail - Free email verification API

Proofy - Quickly validate and verify your email lists.

ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.

Kickbox - Verify your email address lists with our drag and drop interface, or integrate into your app with our API. Prevent fake and bot account sign-ups by confirming your users are real humans with a real email address.