junk mail
When I get junk mail it usually has a yellow line across the top that say's load remote content or move to inbox. Ever since Catalina upgrade it appears briefly then disappears not a big deal just wondering why it vanished.
mine is doing that if the content is loaded. dont know why is auto downloaded only on some message, not all. ther problem is that the message preview is not displaying correctly so i need to load it to see it