I have reported this as a bug at the KDE bugzilla site (https://bugs.kde.org/show_bug.cgi?id=435776). But since it only happens with messages originating from groups.io, I'm bringing it up here.
I use POP3 and KMail2 to process almost all of my email. I have a problem with image quality on messages that originate at the groups.io web site. Here is an example screenshot.
As you can see, the image is all washed out, and the photographed text is hard to read. But it's a rendering problem, and not an image quality problem per se. Here's a screenshot of the same image file, also rendered by KMail. (I selected just the image attachment for display by KMail to make this screenshot.)
Clearly the bug is somewhere in KMail. But it's only triggered by messages that came from grroups.io, so far as I can tell. Is there anything peculiar about the headers that groups.io inserts in outgoing messages that could possibly account for this? Something else about groups.io messages that might affect image quality? Weird metadata in the image file, or something like that?
Any suggestions will be appreciated, and gratefully accepted.
Canyon Lake, Texas