You do understand that conversing and flirting via email, especially if on a work computer or if the emails are going through a work exchange server, means that even if you delete them they can be retrieved if the server is being backed up properly?
Depending on her age and yours, she might be just be fucking with you for sport and the moment she loses interest in the "game" all it would take is her to show her dad the email or worse, one of her parents to check her email and you have no idea if they have any software installed that allows them to keep tabs on their kid.
Keep that in mind. She may be flirting but to the boss, that is his precious daughter he bounced on his knee and will walk down the aisle.
You really need to step aside since it appears all you want to do is fuck her.
What's the age difference?