I am on Sugar Enterprise version 13.3 (upgrading to 14 in August/September). I use HTML to make my email templates and I find that Sugar is deleting any inline width CSS on images. It allows width on tables and rows and other elements, but for some reason it will not leave in the width on an image. This essentially makes it impossible to have a responsive, mobile-friendly email template. I need to be able to set an image to width:100% in order to have it resize to whatever the width of the parent div is. But because Sugar strips out that inline CSS, the images in my email template simply display at whatever width the image file is, which looks terrible on mobile.
Here is an example. As you can see, the header image does not resize to it's parent container div. I have done extensive testing. It is not the email client or email application receiving the email that strips out the image width. It is Sugar doing it.