I cannot seem to find the reason why Outlook 2016(windows 7) is adding extra <p> tags into my buttons

Here is the processed html but MSO 2016

<table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0
style='background:#5950FF;border-collapse:collapse;border-radius:5px'>
<tr>
<td style='padding:15.0pt 15.0pt 15.0pt 15.0pt;display:inline-block'>
<p class=MsoNormal align=center style='text-align:center;line-height:
12.0pt'><a
href="http://retailer.spently.com/ShopifyAna/Link/1234?store=steve-spently&amp;type=OI&amp;url=https://checkout.shopify.com/4637950025/orders/123456abcd/authenticate?key=abcdefg"
target="_blank" style='display:inline-block'></a></p>
<h4 style='margin:0in;margin-bottom:.0001pt;line-height:12.0pt'><span
style='font-family:"Arial",sans-serif;color:white;font-weight:normal'><a
href="http://retailer.spently.com/ShopifyAna/Link/1234?store=steve-spently&amp;type=OI&amp;url=https://checkout.shopify.com/4637950025/orders/123456abcd/authenticate?key=abcdefg"
target="_blank"><span style='color:white;text-decoration:none'>View
Your Order</span></a></span></h4>
<p class=MsoNormal align=center style='text-align:center;line-height:
12.0pt'> </p>
</td>
</tr>
</table>

the extra added bit is

<p class=MsoNormal align=center style='text-align:center;line-height:
12.0pt'> </p>

The original html is

<table style="border-collapse:collapse;border-radius:5px;margin:auto;border:0px none #5950ff"
align="center" cellpadding="0" cellspacing="0"
bgcolor="#5950FF">
<tbody>
<tr>
<td style="border-collapse:collapse;border-radius:5px;line-height:16px;padding:20px"
align="center" bgcolor="#5950FF"><a
style="display:inline-block;text-decoration:none;text-align:center;color:#ffffff"
href="http://retailer.spently.com/ShopifyAna/Link/1234?store=steve-spently&amp;type=OI&amp;url=https://checkout.shopify.com/4637950025/orders/123456abcd/authenticate?key=abcdefg"
target="_blank">
<h4 style="font-weight:normal;color:#ffffff;font-family:&#39;open sans&#39;,Arial,&#39;Helvetica Neue&#39;,Helvetica,sans-serif;font-style:inherit;text-transform:inherit;letter-spacing:0px;font-size:16px;line-height:16px;margin:0px"
align="left">View Your Order</h4>
</a></td>
</tr>
</tbody>
</table>