They work by giving you a random email address that is available for a short time (ex. 10min) and an inbox for any messages you recieve during that time (ex. an email verification message from a Lemmy server)
I didn’t want to recommend a specific one, however Googling “temporary email” should give you several options to choose from.
apple offers one as well if you’re on safari
I have used that service many times
I’ve read about the Apple service for this, but i don’t have an iCloud account.