Add in functionality to existing web form w/php & mysql

I have a form written in php and mysql. Currently, when someone fills it out, the users has to fill out a captcha field. When the form is filled out, an email is sent to the admin telling them to login to approve or deny the contents. If they approve it, the form data is posted to the website. Too much spam is getting in, so here is how we need it modifying: When someone fills out the form, they should need to now fill out the form and fill out their email address a second time. When this email is filled out, a message tells them that a link has been sent to their email box that they will need to click on to verify. Once the link is clicked on from their email, everything will resume as normal. The email will be sent to the admin telling them to approve or deny. If the link has not been clicked within 90 minutes, the entry should be deleted from the database. I'm assuming this will be done using a cron job. It is important to note that no work done on any of my projects should ever be featured in any portfolio other than my own, and my client should never be contacted by you, or receive any test communications during development. Your email address should not be used on my server at all - if you need a test email address, let me know and I can get you one.