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 Checker - Email Checker offers a real-time API and bulk validation for list cleaning.
TrueMail.io - TrueMail.io is an email checker service.
Bulk Email Checker - Bulk Email Checker is an online service used to Verify and Clean Email Addresses. Its Easy to Use, Reliable and used by 1000's of Businesses.
Simple Email Verifier - Simple email verifier is PHP script use Trumail API to verify bulk email addresses.
Verifalia - Verifalia is a web-based email validation that lets users to upload and validate lists of email addresses.