Add-in icons in outlook are no longer loaded properly

Outlook seems to load the add-in icons (e.g. Translate, etc.) in the background and then add them to DOM. This makes an explicit per-image whitelisting within the DOM impossible because the add-in icons are not even added to the DOM in the first place.
The add-in icons are also loaded directly from different vendor domains. This makes a whitelisting rule based on the URL infeasible.

Any suggestions for whitelisting add-in icons are welcome...

trockerapp / trocker