Proofy - Quickly validate and verify your email lists.
Trumail - Free email verification API
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
BriteVerify - Email Validation & Email Verification reduces bounce rates up to 98%. Rapidly verifying email addresses has never been easier, just drag drop and deliver!
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Bulk Email Verifier - Clean up your large mailing lists before you use them. Clean list increases your reputation in MailChimp, AWeber, or Campayn.