Update README.md

README.md

@@ -133,6 +133,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Freelancer](https://developers.freelancer.com) | Hire freelancers to get work done | `OAuth` | Yes | Unknown |
 | [Gmail](https://developers.google.com/gmail/api/) | Flexible, RESTful access to the user's inbox | `OAuth` | Yes | Unknown |
 | [Google Analytics](https://developers.google.com/analytics/) | Collect, configure and analyze your data to reach the right audience | `OAuth` | Yes | Unknown |
+| [mailboxlayer](https://mailboxlayer.com/) | Email validation & verification JSON API for developers | `apiKey` | Yes | Unknown |
 | [MailboxValidator](https://www.mailboxvalidator.com/api-single-validation) | Validate email address to improve deliverability | `apiKey` | Yes | Unknown |
 | [mailgun](https://www.mailgun.com/) | Email Service | `apiKey` | Yes | Unknown |
 | [markerapi](http://www.markerapi.com/) | Trademark Search | No | No | Unknown |