Bulk Email Verifier - Clean up your large mailing lists before you use them. Clean list increases your reputation in MailChimp, AWeber, or Campayn.
Apility.io - Threat Intelligence Anti Abuse API to find out in advance if your users will be good customers. Learn if your users are on an abuse blacklist and decide how to proceed.
Email Verifier - Email verifier app lets you verify email.
TrueMail.io - TrueMail.io is an email checker service.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Simple Email Verifier - Simple email verifier is PHP script use Trumail API to verify bulk email addresses.