It looks like marketo has since allowed for comments to stay in the email, but the image size fix that your code should fix doesn't work now because marketo is stripping out the xmlns attributes from the html tag. When validating the html marketo gives this warning:
line 2 column 1 - Warning: <html> proprietary attribute "xmlns:v"
line 2 column 1 - Warning: <html> proprietary attribute "xmlns:o"
Does anyone know if there's an alternative way to define the xml namespaces for outlook? Does marketo have some way of dealing with this?
I'd really love the option to disable all "code clean up". It's more often the source of issues than the solution to problems in the context of coding HTML e-mails as there's a lot of code that's considered superfluous or incorrect by WYSIWYG editors but that's really necessary in order to have the widest array of e-mail clients render your e-mails correctly. The recent WYSIWYG upgrade, for instance, broke many of our templates, which rendered beautifully prior to the upgrade. The culprit was the new WYSIWYG editors clean up features. Thankfully we had the option to fall back to the last version of the WYSIWYG editor.
Similarly, I've been trying to apply a change to our templates to address the DPI issue in Outlook 2013. They work fine when tested in Litmus alone, but when applied to the WYSIWYG the code clean up feature appears to strip off portions of the code necessary to apply the fix properly. (Still have to do a bit of testing, but I'm fairly certain that's the source of the issue.)
Here's a more recent/active discussion on this topic: Re: Marketo Removing Code for Image Scaling for Outlook at 125%dpi
Much appreciated, Dan! I confirmed, not more than twenty minutes ago, that Marketo is stripping out that code. Didn't take long to test, so no harm done. Thanks for pointing out those existing threads. Looking forward to the fix.