[TemporaryMail]

I don't think there's any value in that though.

You can get all the stuff you mentioned for a fraction of the time and money it would cost to create a disposable email service and then you would also only target the service you wanted instead of sitting around and hoping that a user creates an account at the site you're looking for.

The real value would in the reputation and history of the account (e.g a popular account on a social media site or community) and this isn't a thing that someone would use a disposable email service for as they wouldn't want to risk losing access to the account.