Mozilla has such a service: https://relay.firefox.com/ https://relay.firefox.com/ I also remember seeing one Show HN recently that offered similar functionalit

Mozilla has such a service: https://relay.firefox.com/ https://relay.firefox.com/ I also remember seeing one Show HN recently that offered similar functionality, but couldn't find it via search. The problem is that if the e-mail alias provider becomes popular enough, their subdomains are soon disqualified from being used when registering to sites.