Trumail - Free email verification API
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Free Email Verifier - The first free and accurate email verification service
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!