Q: After ios9 update my emails with attachments won't open and say "message not yet downloaded from server". They were there previously. How do I get them back?

When I open Settings and tap on Battery it lists all the apps used in the last 24 hours and 7 days.  If I tap on Mail it tells me Mail has been on screen and has used 7% of the power used during that period.  It doesn't tell me how much power was used when not "on screen".  By adding up all the app times I get 55mins - which means Mail has been in the background for 50mins and used 7% (on and off screen) - doesn't really tell me if the off-screen consumption is high.  It seems to be about the same as all the other apps used during this period (9 apps).

the discussion wasn't really about power useage but rather the amount of background activiity by the Mail app opposed to actual use by user.

Brantome described it perfectly... "I just wonder what it's meant to be doing in the background when it's not set up for scheduled fetches - imo, it should be almost entirely dormant till  I invoke it. You don't expect a process akin to file transfer to be doing anything after it's downloaded its payload and been closed."

For me, a 20 minutes background activity for 5 minutes of acual useage seems wrong, especially when it's not set-up for scheduled fetches.

The reason they haven't fix it:   Same reason it is almost impossible to disable iCloud - they get kickbacks from the cell providers for all the extra data downloads.

Not one conspiracy theory that I buy into, sorry.

Cellular data charges for the rest of the world other than USA are still very expensive. Imagine most people use wifi to download large volumes of data. Should it transpire that Apple intentionally changed the way the Mail app works and didn't inform people, potentially there would be huge ramifications.

Disabling iCloud is relatively straightforward, albeit that doing so excludes one from using a number of features/services.

I've noticed that messages containing a hyperlink seem to remain on the device, some for over a month without being subject to the not downloaded from server message.  Wondering if anyone else has found this to be the case.

Granted the conspiracy theory of Apple getting kickbacks is a stretch but the whole Cloud concept is based on increasing profits for cell carriers.  Yes, people that have access to WiFi will use it but when you are on the road or live in a rural area WiFi is typically not available.  Millions (billions) of extra downloads for Cloud services, mail, etc. add up to real profits.  I worked in the industry for over 35 years - believe me I know how they think and operate.

I hate to think that but does that explain the huge cost for additional storage on devices when I keep reading how cheap it is for to buy it?  Not only do you pay for the iCloud storage but also for cellular service when out of wifi range.

Yes, I have noticed it as well.  It is also bizarre at how random the deletions occur.  It could be an old message or a new one.  I have also noted that it occurs even when I am connected via wifi continuously.

I can only imagine that this might be a really big problem for them to solve.  I wish they would let us have the old app....

In advance of my call with Apple Support tomorrow, and partially in light of my local Apple Store's suggestion that my ISP was at fault, I setup a new IMAP account and reviewed my iCloud and gmail mail along with my usual pop accounts.

While connected to wifi, I read and took screen snapshots of a variety of complete messages - just plain text, those with urls, embedded images and/or attachments. I then put my iPad into flight mode later in the day to see how each type of account behaved.

While there is a degree of randomness from my limited experimentation, it seems that text only messages which are on the small side, with or without urls, seem to do best across the board and are preserved offline - although one or two pop emails with very small embedded images, like an Amazon order update, are still intact a month after being received. Perhaps those have the image inline, with larger images linking to external image files.

Pop accounts whose messages have been deleted from the server via another client, and those sent from my iPad with non-trivial text, suffer the dreaded "message has not been downloaded from the server" if the original message was anything other than a small amount of plain text (or the few with small embedded images I mention above).

A previously read email on the IMAP account now showed the original small amount of text and url, but the attached file now had a 'tap to download' tag. This was also evident in the sent folder of the IMAP account in an email with an attachment generated from Safari on my iPad.

In a similar manner, non text gmail emails had embedded images replaced by icons named "profile.png" for example.

In terms of iCloud mail (which I guess Apple Store employees would not be as ready to criticise as they did my ISP), messages now showed the 'tap to download' tag for attachments, while previously read/downloaded emails with larger embedded images were now blank with the footer message "This message is only partially downloaded". I did notice a variation on this where very recently read embedded image emails were still fully readable offline, whereas those whose contents hadn't been refreshed when last connected (I.e. not reread) were still blank with the footer message. I suspect the readable ones would lose their content after some time though.

Along with the evidence of the mail app consuming unexpected background time and its overall reduced memory usage compared to pre-iOS 9, along with the time element I allude to in the last sentence above, it suggests to me that mail of any type and from any provider is subject to some sort of garbage collection/ deletion after a period of time. Or has been previously suggested, perhaps the messages have only been retained in volatile memory and not committed to local storage. If it's anything other than straight text or sometimes only small embedded (inline?) images, contents are replaced with links to embedded images and attachments, supplemented with message not/partially downloaded warnings, which will be refreshed on re-connecting for non-pop accounts. Unfortunely, where another client has deleted a message from the pop server, there's nothing to refresh and we get our headline error for our pop emails with no means of retrieving the previously downloaded content.

While minimizing storage  is laudable, I personally feel that removal of the contents of previously downloaded and fully readable emails is a step too far. By all means tidy the mail app's local storage where the user explicitly requests deletion, but leave everything else untouched...

Postscript: on re-reading this, it occurred to me that the tidying up process might be discarding information it can retrieve again online, while preserving locally the data it can't. Unfortunately, that doesn't work for Pop mail that deletes the server copy after retrieval. Nor does it seem to allow later offline reading of non-trivial mail no matter what the source or protocol.

By the way, just within the past day or so I've noticed that my downloaded email is lasting less than 12 hours (est.) before they disappear, which effectively makes them good for about one read, as they're replaced with "the message" by the next day.  Seem like they used to stick around for at least 2-3 days.  Well, for years they stuck around forever (unless manually deleted), but I don't need to remind anyone here of that.  Anyway, pretty amazing that this hasn't been corrected.

For what it's worth - worth nothing unless this forum is watched by folks on the iOS team - a check of battery background usage currently shows 58% for Mail, 12% for Altamail.

I think your postscript is right on. My temp fix is to keep all POP emails on the server. Not my preference, and it's gonna be a pain to clean up later, but it's working for now (as long as I have wifi or cellular data access).  

Regardless, this is not how POP is supposed to work. They have impropearly implemented the protocol in a major way. I think I'll go file another feedback form on www.apple.com/feedback.

While the strategy of not deleting POP mail on the server will allow previously downloaded emails to be refreshed on reconnection to the server, I believe my limited testing potentially shows that across the board, for me at least, all emails (POP, IMAP, my ISP, Gmail, iCloud or whatever) are subject to some time/resource driven memory saving routine on the assumption that the content can be recreated from external sources when the device is re-connected to its mail server. If they can't, like in the case of mainly text messages, perhaps with urls and/or inline images, they're left untouched. The impact of this is most visible for POP accounts where the message may have been deleted from the server by another client and therefore can't be refreshed.

So maybe us having focussed on POP is a wee bit of a red herring - I'm beginning to think the culprit is an over zealous background mail tidy routine that assumes we'll be connected most of the time,  at least when we want to read our emails, irrespective of whether we had already downloaded and read them or not.

Bingo!! I believe this and some other previous emails lend support to my theory that the Popgate and other quirks with the IOS 9 upgrade have to do with thr new OS ability to do upgrades without having to remove apps and other material. The new IOS can delete the apps and then put them back in because your apps are in ICloud. Content such as documents is often also in ICloud. Music is in ITunes. Email, however, has no "backup" so once it reaches either a size and/or time limit it has to go. Apple is not in any hurry to fix this or is having trouble doing it because to do so would require rewriting the entire upgrade routine. You would have to have the programming delete something else.

THis explains the erratic behavior of email in the new IOS. It also explains Apple employees shifting to a blame the messenger strategy. That was my experience when I talked with Apple support.

My prediction is 9.2 will not solve the problem.

Again the larger issue is whether IOS can compete in the new market of tablets that can operate like laptops. As many reviews have noted the new ipad Pro is stunning, but it cannot compete with new offerings such as Microsoft's Surface.

I Am going to predict--and hope--Apple will run its tablets on OS. This, of course, will not work for phones or the mini, but that is the way it needs to be. Right now the IPad is just a big IPhone when it should be a little IMac or MacBook.

Best wishes for a good Thanksgiving to all the posters and to the Apple programmers trying to fix this.

I'm not too sure that a quick fix couldn't be effected if my assumption that a background tidy routine is the real culprit. If that were the case, they could skip this routine for POP accounts which we see suffering the greatest impact thru data loss. That wouldn't resolve the issue of non-POP email being contracted in the assumption that it would be refreshed on reconnection/ rereading, but again, a configurable option on each account as to whether we wanted such a routine to run would at least offer us the choice.

Given that we haven't seen any progress and scant acknowledgement or awareness of this across the board from Apple, it would however suggest that my summation of the issue is far off the mark - or Apple don't see it as an issue requiring priority attention. Either way, we'll never know. At least third party mail app providers are accruing some benefit