A disposable email address is a temporary address from a service such as Mailinator or 10 Minute Mail. People use them to sign up for something without giving their real address; many stop working within minutes or hours.
Why they matter
- They don't belong to a reachable person, so emailing them achieves nothing.
- Many expire, so later emails bounce.
- Some services publish their inboxes openly, which is a privacy risk for anything you send.
Where they show up
Mostly in sign-up forms and scraped lists. A business lead list shouldn't contain any; if it does, the source is poor.
Catching them
Email verifiers keep lists of disposable domains and flag them. Remove every disposable address before sending. mailzy also refuses them at sign-up. Check addresses with the free email validator.