iOS 9 generates problems with emails, or at least that's what some iPhone, iPad or iPod Touch users have experienced after installing the latest version of the operating system for their terminals.
More precisely, some POP e-mail accounts have problems opening e-mails that contain attachments, the Mail application a iOS 9 displaying an error message that says: Message not yet downloaded from server, The message has not been downloaded from the server yet.
For now, the problem seems to be related only to these POP email accounts and it seems that it doesn't matter if the email the user is trying to access is old or new because the error is the same, the problem persisting in all situations.
Simply deleting an email and re-adding it in the Mail application does not seem to solve the problem, but using alternative email applications seems to be a quick and complete solution for it, so if you encounter it you at least know how to read your emails like POP.
I have exactly the same issue. Many of my old mails on my iPad just say not yet downloaded from the server. I am using a pop account on both my iPad and windows live mail. I have tried deleting my email accounts and adding back in. Even some emails that were received this morning are now showing as not being downloaded from the server.
Separately, it appears that avoiding the use of a Wi-Fi connection to load emails is an alternative method of viewing some attachments, but of course the existing images for them will not be able to be loaded by the operating system's native Mail application.
Aware of the problem, those from Apple stated that the error only appears if users choose to delete a copy of the received email from the servers, but if this option is disabled, users can no longer access the trash and sent folders, so solving the at Apple it is not complete.
Apple is investigating the email problem in iOS 9, but it is hard to say when it will find a solution.
