One thing worth checking - make sure that it works properly in IE after clearing the cache. It might be that it's not a browser problem, and that you're seeing cached images in IE that aren't present in Edge.
We're trying to put together a newsletter using some templates (HTML) in our back office system, that we've used perfectly before. Now, when we use Internet Explorer the photos appear correctly, when we use Edge then they don't and its just a block box with a white cross in the middle. This issue has come about after we implemented some IT security a few months back, so I assume its just a setting on Edge that needs to be toggled but not sure what!!
Any ideas?
One thing worth checking - make sure that it works properly in IE after clearing the cache. It might be that it's not a browser problem, and that you're seeing cached images in IE that aren't present in Edge.
Are viewing problems restricted to one machine or many, one location or many?
Are the images hosted in the same location as the newsletter?
What does it look like using Firefox & Chrome? That might narrow things down a bit.
Chrome is far more reliable than the others.
The images - are they contained within the body of the email, or are they hosted remotely on a web server somewhere and being linked to with an <img src.../> tag?