Same issue here, devastating to open rate (and of course the resulting click through rate). Coming out of a pandemic, not acceptable. Very LARGE expensive number of subscribers here, so planning to switch providers if this isnt resolved this week.
The workaround that support offered was hillarious: it allowed images to show up, IF a recipient has customized their outlook settings to go for http hosted images and not https. Not suprisingly, our resend to non openers (after going through the painful process of editing the text links in each of the images in the email, which we didnt budget time for), got a very low open rate & click through rate because an even larger number of folks did not see the images.
Interestingly, we were also not able to edit the icons for social media that appear at the bottom. Those are like widgets outside of our control (although if we'd known, we'd have added our own images).
The issue appears to be that the domain hosting the images is on some blacklists, as per some research. Even norton has the image-hosting-domain of CC flagged.
Its too easy to change domains as the first step toward resolving, and would probably work - takes no troubleshooting. Troubleshooting would be understandably tough.
Would like to know other folks' recommendations for alternatives to Constant Contact. is great, but way to expensive when you have above 100K subs on the list. We switched from to Constant contact for better open rates, and for a reputation of constant contact to have less emails showing in the gmail promotions tab. The latter did not pan out, but its understandably based on email content (theoretically). We did not opt for one other up and coming email service provider that I can't recall the name of, because they can't do DKIM records for improved delivery rates.
