Emails that contain HTML for the Subscribe by email plugin

The site name is used as plain text in the email subject, body, and from name of the subscribe by email emails.

Jane & amp; Joe& #039;s Blog <admin@joes-blog.com>
Subject: [Jane & amp; Joe& #039;s Blog] New blog post

Dear admin,

New post was posted on Jane & amp; Joe& #039;s Blog.

Thanks,
Jane & amp; Joe& #039;s Blog

This seems to be a problem on another plugin - https://premium.wpmudev.org/forums/topic/emails-contain-html-entities-from-the-site-name

[Edit: needed to add a space after the ampersand in my example for it to show the plain text properly.]