How the signup step works
Facebook sends a confirmation code or link to the email you register. Paste the temporary address from this page, submit, and watch the inbox here for the message. If it arrives, enter the code to confirm the address.
That handles the immediate email step and keeps Facebook notifications out of your personal inbox.
Why this is risky with Facebook
Facebook frequently asks accounts to re-verify — by email, and very often by phone or photo ID — especially for new accounts or anything its systems flag. It is well known for blocking disposable email domains, so the confirmation may never arrive at all.
The bigger problem is recovery. Once the five-minute inbox expires, you cannot receive a password reset or a security-checkpoint email. If Facebook locks the account for review, an address that no longer exists means you have no way back in.
A safer approach
For any Facebook account you want to keep, use a real email you control so resets and security emails can always reach you. Reserve temporary email for genuinely disposable accounts you are prepared to lose.
If the confirmation does not arrive with a temporary address, that is usually the disposable domain being blocked — trying another temp address will typically fail the same way.