I have a form that collects credit card data and sends that data by email to me. I would like to encrypt that email so the credit card data does not get stolen in-transit. Can anyone tell me an easy way to encrypt email using PHP?

You need some kind of 2 way encryption algorithm. Look at http://us2.php.net/manual/en/ref.mcrypt.php and http://www.tonymarston.co.uk/php-mysql/encryption.html

SSL for a start.

PHP is server side therefore encrypting on the client with PHP is just not going to happen.

Make sure you server has https (which should be standard when dealing with such data). Then you may feel a little happier.

Ibbo