Proofy - Quickly validate and verify your email lists.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Trumail - Free email verification API
BriteVerify - Email Validation & Email Verification reduces bounce rates up to 98%. Rapidly verifying email addresses has never been easier, just drag drop and deliver!
Bouncebuster by Overloop - Bouncebuster is a real-time email verifier that helps you fight bounce & increase email deliverability.
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.