My client did not receive the authorisation code after I "Send Will".
Ask your client to check the spam folder. Depending on the email server, this may take up to 30 seconds [on gmail this is almost instantaneous].
For security reasons, the authorization code is only valid for a limited time ~5 - 10 minutes. In the event the code is not invalid, try "Resend code" with the steps below
In the event that your client still does not receive any email, try sending it again by clicking the "Resend code"
Some email servers may block us. This is out of our control as this is dependent on the email server settings on your clients side. If your client still doesn't receive the email and is using an uncommon email server (e.g. @xyazas.com), try switching to send a code to his / her gmail account instead.
Do not attempt to keep resending the email in a short span of time as depending on the email server, the future emails may be blocked entirely. If that happens, your client needs to "report as not spam" any existing similar emails before trying again. Otherwise, you might need to send it to another email instead or change his/her email settings / contact their email server to unblock us.