How to pass an URL in mailto's body

I need to send an URL of my site in the body so the mail recipient can click on that to join my site.

However currently mail client renders the mail like this:

Link goes here http://www.example.com/foo.php?this=a

The URL is truncated on the & symbol, thus the whole process of joining failed. How can I pass the URL like http://www.example.com/foo.php?this=a&join=abc&user454 in mailto body?

My current HTML is the following:

<a href="mailto:test@test.test?body=Link goes here http://www.example.com/foo.php?this=a&amp;really=long&amp;url=with&amp;lots=and&amp;lots=and&amp;lots=of&prameters=on_it
">Link text goes here</a>