Stop worrying about designing gorgeous buttons using progressively enhanced VML and CSS.
Use this instead.
Write email code in Jade, using +button for the mixin:
include ../bullet-proof-button.jade
// ... Jade ...
+button( bgcolor = '#536895', color = '#ffffff', border = '1px solid #1e3650', border-radius = '4px', height = '40px', width = '200px', href = 'http://buttons.cm/')
| Connect with us
// ... more Jade ...And get a much more intense output, voila!
<div>
<!--[if mso]>
<v:roundrect xmlns:v="urn:schemas-microsoft-com:vml" xmlns:w="urn:schemas-microsoft-com:office:word" href="http://buttons.cm/" style="height:40px;v-text-anchor:middle;width:200px;" arcsize="10%" strokecolor="#1e3650" fill="#536895">
<w:anchorlock/>
<center style="color:#ffffff;font-family:sans-serif;font-size:13px;font-weight:bold;">Connect with us
</center>
</v:roundrect>
<![endif]--><a href="http://buttons.cm/" style="background-color:#536895;border:1px solid #1e3650;border-radius:4px;color:#ffffff;display:inline-block;font-family:sans-serif;font-size:13px;font-weight:bold;line-height:40px;text-align:center;text-decoration:none;width:200px;-webkit-ext-size-adjust:none;mso-hide:all;">Connect with us</a>
</div>