What Is a Disposable Email Address?
A disposable email address is a temporary inbox, often valid for minutes, used to receive a confirmation message without handing over a real address. Dozens of services hand them out instantly and for free.
Detection is a list problem, and lists go stale. The harder cases are services that give every signup its own random subdomain, so a simple exact-match list never sees the same domain twice. Matching on the parent domain is what catches those.
Blocking them outright is a judgement call rather than an obvious win. Some people use throwaway addresses because they are wary, not because they are malicious, and rejecting them silently loses enquiries you wanted. Weighting the signal alongside others is usually better than a hard block.
A disposable address on a job application means something different from one on a newsletter signup. The same signal deserves different weight per form.
In WebForms
WebForms scores disposable domains rather than rejecting them, using both an exact list and suffix matching for services that rotate subdomains per signup.