Gravity Forms is a premier WordPress plugin that makes it easy to create powerful forms on the fly.
You can find more information here.
How this Gravity Forms + TrueMail integration works
1. Add new record to a Gravity Forms account
2. Zapier sends the email to be verified with TrueMail
3. Zapier updates the existing Gravity Forms record with TrueMail result code in a custom field
• Gravity Forms
Gravity Forms Triggers