PHP Email Response Add Delay

Hi guys,
I've created a PHP form for my website and have added an email response to it to be sent to the user once they've submitted their details. What I'd like to do is add in a delay of some sort so that the user doesn't immediately receive the email. I'd like to pretend that it's a real person emailing them back instead of them receiving an email 2 seconds after clicking the submit button.
Any ideas how I'd do that?
Many thanks

See original post by martin12532