Why doesn't Microsoft Outlook respect list styles when sending HTML emails?

I have the following code and for the life of me I can't get it to work in Microsoft Outlook.

<ul style="margin-left: 50px; line-height: 50px; list-style: none;">
    <li style="font-size: 1.5em; list-style: none;">[UniqueCode]</li>
</ul>

Is there another way to achieve the same result? I am attempting to send a HTML email to a group of people.