How to avoid "To protect your privacy, some pictures in this message were not downloaded" from appearing in Outlook

I've created an email newsletter with a nice banner image, but unfortunately all of my Microsoft Outlook users are getting this message:

"To protect your privacy, some pictures in this message were not downloaded"

The problem is that the banner image is being served from our private web server, which presumably is being flagged as "not-safe."

I understand the various reasons why Outlook prevents the images from auto-loading (tracking pixels, malware, etc), but is there a way to somehow serve the image from a "safe-server" that avoids all of these hurdles?

If we serve the image from a CDN (say Cloudflare) would Microsoft then say the image is safe to auto-load? How do other services get around this problem? Surely Microsoft isn't blocking every possible image from auto-loading?

There are "white-lists" and settings within Outlook to auto-load images, but I would prefer something that's doesn't force the recipient to change their settings.