I am load testing a registration form on my internal website and it has one field which must be unique (email address). I’m using JMeter (following this tutorial). I have a HTTP Request under the Recording Controller in a Thread Group in my test plan.
How do I configure this HTTP Request to add a random number to my email address field (see screenshot)? My company’s internal test email server will accept anything at its domain (so like testing347387438@my-internal-test-email-server.com). How can I configure JMeter to add a random number to the email address which should make it unique?

You can use random function.
So your email address will be like: