How do I add newlines to email shares?

I want to add a “signature footer” and referral / tracking code to my email shares.

I’m editing this file:
wp-content/plugins/sassy-social-share/includes/class-sassy-social-share-sharing-networks.php

Specifically, the line:
’email’ => ‘<li class=”%li_class%”><i %style% alt=”%title%” Title=”Email” class=”heateorSssSharing heateorSss%ucfirst_network%Background” %amp_email% onclick=”window.location.href = \’mailto:?subject=\’ + decodeURIComponent(\’%post_title%\’ ).replace(\’&\’, \’%26\’) + \’&body=\’ + decodeURIComponent(\’%post_url%\’ )”><ss style=”display:block” class=”heateorSssSharingSvg heateorSss%ucfirst_network%Svg”></ss></i>’,

(I edited this part: body=\’ + decodeURIComponent(\’%post_url% I put stuff here \’ )” )

But what is the syntax for newlines? I tried the following, but none worked to create 2 newlines: \n, \\n, br tags

Something to do with setting the content type of the email?

Thanks!