Mail message not downloaded from server

[FlyingCapt]

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?

 

[dhewson777]

If possible with your email provider, use IMAP rather than POP3 to sync emails between the server and multiple devices. This method keeps a copy on the server until you delete it.

POP3 will attempt to download, then remove the email from the server unless you have "leave a copy on the mail server" checked.

 

[giradman]

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?

As already mentioned, POP3 (Post Office Protocol) is an old standard that was fine to download your mail in the 'ole days' when many of us just had one computer @ home and the option to MOVE all the messages from your mail server to your computer was desired (i.e. the days of having those 'mail clients' on your computer) - as already suggested, you should either check w/ your mail service provider (simply log into their mail website on a browser) to see if your messages can be left on the server on their POP service; if not, then you need to switch to an IMAP (Internet Message Access Protocol) protocol which keeps your mail on their servers and allows access to them via multiple devices.

Also, you might want to tell us if you have recently switched service providers (I use Yahoo Mail) and if you have multiple providers, is this a problem w/ all of them? Also, note that El Capitan is not an iOS, but the newest version of Apple's OS X (specifically, 10.11.0) - I've not updated my iMac or MBPro on Yosemite yet, waiting for the first minor update? Dave