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.
I used https://temp-mail.org/ on Reddit quite a bit. Quick & no registration needed. Just keep in mind that you cannot restore your account that way.
but reddit doesnt require an email? I never used an email for all my accounts Id create a new account every few months
It does now last I checked, but didn’t use to.