Your test email displays an image that is cutoff.
Many versions of Outlook (2007, 2010, 2013, 2013 DPI, and 2016) actually have a maximum allowed image height. If an image is getting cut off or clipped in one of these versions of Outlook, it's very likely that the image itself is more than 1728 pixels tall.
Why do images taller than 1728 pixels get cut off?
These versions of Outlook display emails using the Microsoft Word 2007 rendering engine, which contains a maximum image height of 18 inches (which translates to about 1728 pixels). Images taller than this will have the excess height cut off from the top of the image.
There is nothing to magically fix this issue. Images taller than 1728 pixels will need to be cut into smaller images and stacked within the email design.