using mailto in HTML to prompt the user to email

I am trying to use the tag "mailto" in an HTML file to prompt the user to email me. Specifically, I want to have the subject and the body of the email message already filled in when the user sends me the email.

So far, I have managed to have a hyperlink where the body is already filled in:

<a  href="mailto::username@gmail.com?body='test'">this works</a>

HTML:

I have also managed to have a hyperlink where the subject line is already filled in:

<a  href="mailto:usernamegmail.com?subject='the subject'">this works too</a>

HTML:

But I have yet to figure out how do combine the two:

<a  href="mailto::username@gmail.com?subject='the subject and 
the body'?body='test'">help</a>

HTML:

Does anyone know how to do this?

 

Here you go.