Limit password reset email requests

A user can send as many password reset request as he want, by clicking "Forgot your password" .

For some user may take few minutes until they receive the reset email (depending on their email configuration, anti-spam filters and other).
By sending multiple reset request the user may:

• Mistake the last email with other from the email thread and click on an old link
• Or he may not receive all the emails

I have identified two situations when the link from the email expire and the user  gets "Wrong parameters" error. And this error message may not be very clear for him why it is displayed.

• an other request is sent
• the link was already accessed (it doesn't take into consideration if the password was changed or not)

So to avoid these confusion, it would be nice to display a message like: " An email was already sent. Try after 5 minutes.", when a request has already been sent.