Sometimes, you need to get “something” free on the internet.
In return of that “something” you have to submit your own email address (you know the drill).
Unless it is something truly worth it & interesting, I am not willing to give up my email address.
This is why we need disposable email addresses.
You get an email address with a validity of about 15 minutes. Within 15 minutes, you can send and receive emails. After that, email is gone forever (edit: validity depends on the website – some of them have up to 2 hours. Please check before use).
Here is a list of top 10 disposable email suppliers: