I keep getting this message randomly on my POP Mail on my iPad 2 running IOS 9.0.2. There have been numerous threads posted on this subject, but I haven't seen any positive solutios or reasons for the problem. What is causing this problem, and what is the fix? Also, when I download my mail on my MacBook Pro, running El Capitan IOS, and the iPad is on the Mail app, I lose ALL my email on the iPad with the "Message is not downloaded from the server" problem. Can POP mail not be downloaded onto two computers at the same time? Is it possible to get my mail back on the iPad?