Why am I suddenly getting this popup? Running Mojave with latest updates. This is NOT the only popup I'm suddenly getting. A couple of times a day I'll be on my browser and suddenly I get a MAIL popup screen that takes up half the screen on the left side. If the latter is caused my some keystroke I'm doing, I'm not aware of it. I AM NOT running the latest beta macOS. Are both of these popups a preview of the upcoming Catalina? IF so, I don't want Catalina when it debuts later this year. The only other Apple product I have is the IPXS and an iPad Pro 10.5".