PHP MySQL Database Auto Update from Emails

I have a test database where a PHP script pulls in data from an email account and parses firstname and lastname into the database. A customer clicks a button to download a .pdf document. He/she must enter a first and last name and email. The form checks against the db. If it does not find the names, the customer is given an error message. If it does, the .pdf document is automatically downloaded. I want to make sure the script runs automatically and is reliable.