Image files sent with Apple Mail 16.0 cannot be downloaded by some recipients

A long-standing problem has popped up again. Images that I send from Apple Mail (from multiple email accounts) cannot be downloaded by some recipients. The problem, says one person experiencing it, is that the images wind up embedded in the email so she can't get them out. She can see at least some of the images, but cannot download them. She uses Outlook in an academic environment. Others to whom I sent the same photos report no problem with mail they receive on Gmail or Yahoo. When I send the emails with the files attached from the webmail on my personal domain, the person on Outlook can download them.

I have not done extensive testing, but this seems very similar if not identical to a problem I had for the past few years with clients who could not receive image attachments emailed from an earlier version of Apple Mail. They complained about no attachments, but could receive them when I sent them from a webmail account. I am no longer writing for those clients, so I cannot retest that problem. In both the current problem and earlier ones, the pictures had to be downloaded for the recipients to use (either images for use with an article or family photos).

Is anyone else experiencing this? Are you able to confirm the symptoms and the particular problem? Thanks.