In Outlook 2016, installed from an Office 365 subscription, when I look in my inbox at emails received from Chargebee notifications, they look really bad:
instead of showing just the text, it shows the first picture URL, and that's a pretty long URL.
The preview text should be changed to escape the picture URL.
I have raised this as a feature request and tagged you to it. We do not have a firm ETA on when will we take this up, however, we will certainly circle back to you once we start working on it.