Spam is a problem. You want to allow people who genuinely want to get in touch to see your email address, but doing this invariably leads to you getting thousands of spam emails.
One solution is to hide your email address in an image, but it can be a pain to create an image for every email address you need. A better solution is to use the PHP GD functions to create an image at runtime so that your email address is displayed, but is completely unreadable to spammers.
To to this you will need to create an image tag on your website, here is an example.