NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.

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

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

BriteVerify - Email Validation & Email Verification reduces bounce rates up to 98%. Rapidly verifying email addresses has never been easier, just drag drop and deliver!