In my email views, I usually just do something like...
<dl>
<dt>Name</dt>
<dd>Value</dd>
</dl>
Should I be doing it like this?
<html>
<head></head>
<body>
<dl>
<dt>Name</dt>
<dd>Value</dd>
</dl>
</body>
</html>
In other words, like I was marking up a standalone document?
I guess I can safely assume any web based email client will strip it out?
What is the right way?
The right way is to follow the HTML standard. You can validate your HTML page here.
Your mail client should follow it and should throw away what's not supported or what's insecure like javascript.
UPDATE: after several down votes from people that gets angry when you tell them to follow standards, I'll expose some reasons of why following standards could be beneficial here: