Hello! I have attached two screenshots. This issue occurs using the Microsoft Outlook mobile app on my iPhone 6S. I don't see the issue when the phone is rotated horizontal or when I run the tests in EMMA.
Hi Gary -- I'm not able to test to the Outlook mobile app, but I'm seeing it coming through as expected on Outllook.com and all other email clients. That tells me that it's not a template spacing issue but rather an issue with how that specific mobile email client is rendering your email content. This seems to be a pretty isolated issue, and one that I won't be able to entirely identify since I can't actually test to it.
Once common issue with Outlook clients is pagination, which basically means that Outlook adds a page break wherever it thinks one is necessary. That's the most common cause of the extra white space you see above. While I'm not seeing that in the other versions of Outlook, it's a likely culprit for you spacing issue on mobile. You can work around this by forcing those page breaks elsewhere, playing your layout a bit and adding/removing space in your content. There's more on that here!