Disposable email address
A throwaway mailbox from a temporary-mail provider, designed to receive one signup confirmation and then be abandoned.
Disposable providers hand out an address that works for minutes or hours. People use them to get past a signup wall without giving a real address. The address is genuinely deliverable while it lives, so syntax and SMTP checks both pass: only knowing the provider identifies it.
Detection therefore comes down to a maintained list of disposable domains, refreshed continuously because new ones appear constantly. Our list is rebuilt daily and currently covers tens of thousands of domains.
Blocking them outright is a product decision, not a technical one. For a paid signup, refusing disposable addresses filters low-intent accounts. For a newsletter, it may just push a curious reader away.