How long does it take for an email gift to go through?

Welcome to the Apple Community.

When I send them they arrive in seconds.

Ask the recipient to check Mail rules and filtering, the verification mail may be going to a junk folder or even being deleted altogether.

Also see if you are able to resend the email by following these steps.

If the problem persists, select the content which is causing a problem and use the 'Report a problem' button in Your Purchase History using your computer.