The Difference Between Temporary and Permanent Email
They look the same in the To: field. They are wildly different in lifetime, identity, and risk profile.
A permanent email — your Gmail, your iCloud, your work address — is meant to last for years. A temporary email is meant to last for hours. That single difference cascades into everything else.
Identity
A permanent address is wrapped around your real identity: a name, a phone number, sometimes a recovery card. A disposable address is identity-free. Nobody verified you to create it. That is a feature, not a bug, when the only purpose is to receive a confirmation link.
Recoverability
If you forget the password to a Gmail account, you can recover it. If you "lose" a disposable address, that is fine — the whole inbox was designed to be lost. Never use a disposable address for anything where you would care if it disappeared mid-session.
Trust by other systems
Banks, governments, and many SaaS products explicitly block known disposable-email domains. They want a long-lived address they can reach you at later. That is a reasonable demand for those services and a reason to keep your real address for those exact use cases.
Use the right tool for the job: permanent addresses for relationships, disposable addresses for transactions.