missing scheme in email body url

Some mail service providers (Yahoo Mail exhibits this at the moment), do not like links that do not have a scheme(http/https for instance) and will make the link non-clickable by removing the href. The fix is simple:

<!-- link is not clickable -->
<a href="www.google.com">Google</a>
<!-- link is clickable -->
<a href="https://www.google.com">Google</a>