For any business or website that relies on user or customer interaction, communication is important, and often the only point of contact a business may have with that customer is an email address. This is where email validation can lend a helping hand; as long as mail can be successfully sent to an address all is good, but if there's some issue causing failed delivery and other errors, better to know about it. Email Pie is a free, JSON API that provides a simple way to validate email addresses.
Email Pie provides users with an easy-to-use tool that lets them know if an email address is legitimate or not. It covers things like checking the email format, checking mx records, identifying spelling errors, invalid characters or missing @ signs, and making sure that the domain is configured to collect email.
Sample code for Email Pie API integration is provided in Python, Ruby and PHP, and returns JSON. The API is free for developers to use for now, but the company limits API calls to 1800 per hour. Further information is available on the website.