Response email not in HTML

For some strange reason I have a reply email using Mail2 and the HTML box is ticked. The message is HTML (seen below) but is coming through as shown below!!!

MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/html; charset=UTF-8

<p>Dear Wayne,</p>
<p>Thank you for requesting a quote from the Training Room Hire Company, a member of our staff will call you shortly.</p>
<p>Meanwhile, please check out below what our clients say about us…</p>
<p>“I have travelled all over the world ...the service here is 5 star! Staff are brilliant and everyone extremely helpful”<br />
- Kurt, Ops international</p>
<p>“Always welcomed with a smile. Professional, friendly staff and the facilities provided were excellent. Thank you!”<br />
- Sarah Hacker, Asta Development, UK</p>
<p>“I've Overall experience is always good! The best thing about TRHC is the truly excellent staff-small touches and attention to detail. Very welcoming for delegates.”<br />
- Jackie Smith , balance-global, UK</p>
<p>Read more go to https://www.trainingroomhire.co.uk/testimonials/</p>

https://www.ads-software.com/plugins/contact-form-7/