Null Bounce is an email validation tool that helps companies send emails to real users and 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.

To verify each email, Null Bounce uses several different methods, including SMPT-validation and some provider-specific methods. Role-base, disposable, and free emails are detected as well. All duplicated emails are free.

Here are some features of Null Bounce:
1. Free Trial
2. SMTP Verification
3. ESP-specific validation
4. Anti-greylisting method
5. API Access
6. Disposable emails cleaner
7. Catch-All Domain checker
8. Email duplicates checker
9. Role and free email detection
10. Unknown results are free