Email doesn't need postage, right? Is that old hoax about the postal service charging per message finally coming true? Not really. But PostageApp may be a service worth paying for if you want to send email from your application.
Twilio SendGrid's Email Validation API is now publicly available. The API validates email addresses by searching in real-time for errors such as typos, inactive, non-existent, disposable and shared mailboxes. Further, the API checks for proper syntax, DNS records, disposable domains, and more.