Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
CampaignKit - Email Validation for marketers. Detect invalid and malicious email addresses in your email lists.
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Null Bounce - Null Bounce is an email validation tool that helps companies decrease the bounce rate for email campaigns. Also, the service is available as an API, which can be used, for example, on sign-up forms to ensure that user submits a valid email address.
Email Verifier - Email verifier app lets you verify email.
Captain Verify - Captain Verify is the best solution to Verify & Clean the validity of your emails.