Bounce Emulator

Learn how to test your SMTP client’s behavior when the server responds with an error. 

How to use Bounce Emulator

Constructing the address

The recipient’s username should start with bounce+ and contain the response in URL-encoded form: bounce+550+no+such+user+here@inbox.mailtrap.io .

To create it, use https://www.urlencoder.org or any other URL encoding solution.

Tip: You cannot use capital letters because email addresses are converted to lowercase by any responsible SMTP client. But you can use URL encoding to express capital letters: bounce+550+%4Eo+such+user+here@inbox.mailtrap.io .

Using Bounce Emulator with an email client

Just use the inbox.mailtrap.io host with any email client or application and send an email to bounce+451+server+unavailable@inbox.mailtrap.io . 

Using Bounce Emulator with Sandbox

If your application is connected to Email Sandbox SMTP, send an email from the application to bounce+454+authentication+required@anydomain.com , and your application will receive a bounce response from the Sandbox SMTP server.

Note: This feature does not work with API, as bounce codes are specific to SMTP.