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’ve read about the Apple service for this, but i don’t have an iCloud account.
I have used that service many times