Mailtrap is an email testing tool that allows you to test your email applications in a safe environment without actually sending any emails to real users. It's perfect for development and staging environments where you need to test email functionality, but don't want to risk sending out actual emails. Mailtrap provides a fake SMTP server that your application can connect to, and all outgoing emails will be captured by Mailtrap instead of being sent out. This way, you can inspect the emails and ensure that they're formatted correctly, contain the right information, and are not going to spam anyone when you eventually switch over to using a real SMTP server.