Possible to include HTML within php define()? : I want to know if it is possible to include HTML code within PHP define(). 

I use define() for emailing purposes. I use it to send a verification email to users who register on the site, however, instead of a plain, old boring text, I want to know if it would be possible to include HTML elements, such as headers, images etc..

Here's my current code:

    define("EMAIL_VERIFICATION_CONTENT", "Activate your account by clicking the link below");

So the above code includes the email content with simply just text. I wish to add images, headers and colors into the email etc.

Any help and guidance would be great.
Thank you!