Guys, I have great news. You don't ever need to touch the HTML of an email template again.
Simply go to www.knak.io and build your template. You can customize it with your brand colors, logo and social links, all without needing to know any HTML.
From there, you bring it into Marketo, and it just works. We've already set it up with all the Marketo editable regions (and it will look right on your brand standards). You never even need to look at the code. If you're like me, I look at code and it breaks it.
We have tested these template extensively using Litmus, so Outlook 2013 is no problem.
Try it out now. Build your first template free:
www.knak.io