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?

Below is a copy of the explanation that Will616 posted. It is the best explanation I've seen of what is going on.

------------------------------------------------ Copy of Posting ------------------------------------------

I have the same issue. I have identified at least 4 other
separate threads on the apple forums as well as numerous threads on other forums.
I will attempt to précis them here and also provide links so you can read
through my sources yourselves. Note there is, as always, a significant
amount of duff information, guessing and questionable fact obscuring the useful
evidence.

1. 1. This issue only appears to be affecting people with email
   accounts set up for pop/smtp.
2. 2. Following upgrade to iOS 9 / iOS 9.01 and possibly the 9.1
   beta as well, email content is removed from the iOS device resulting in a
   sudden decrease in the storage required for the mail app.
3. 3. Emails that may have been present on the device for many
   months and accessed multiple times in both the inbox and sent items will be
   randomly replaced with the basic placeholder information (similar to a IMAP
   case prior to download) but with the body and attachments replaced by the
   statement: This message has not been downloaded from the server.
4. 4. Deleting the account and setting it up again from scratch
   does not resolve the issue and will result in the loss of all the email
   placeholders - further increasing your loss of knowledge so you can't even work
   out what you've lost (tried it with one of my 4 accounts - won't be doing any
   more of them). I forwarded a lost message that was held on my iMac
   archive back to the newly set up pop/smtp account and it appeared and was
   accessible for about 12 hours before reverting to 'This message has not....
5. 5. Switching the account to IMAP if you go for a delete and
   re-setup will also result in the loss of all the email placeholders but will
   'probably' solve the problem (within the limitations of IMAP) for future
   emails.
6. 6. This affects all iOS devices - iPads (all gens on iOS 9)
   iPhones (all gens on iOS 9). It is not affecting the same email accounts
   on our OS X machines (an iMac)
7. 7. This issue affects you irrespective of you country, internet
   provider or email provider - the discriminator is the use of pop/smtp. It
   is disappointing that a number of apple customers have paid for support and
   been palmed off with this as a possible cause.
8. 8. pop/smtp is not legacy or backward compared to imap it is
   just different. We use pop/smtp for 3 reasons: we don't want emails left
   on the server where a questionably secure environment could be compromised; our
   family want the ability to all download the same email to multiple devices
   without affecting each others ability to do so; we want one master device (the
   main iMac) to be the deleting device that holds the archive of all emails
   (right now we are very pleased we have this as all the iOS devices are scorched
   earth right now).
9. 9. Some emails appear unaffected - I cannot identify any rhyme
   or reason to this. Old, new, addressee, - there doesn't seem to be a
   pattern. Can't say for certain but it seems that more are being affected as
   time goes on. If you are affected and you have the only copy of an email
   currently and you are going to need it again.....get it somewhere else ASAP!!!
10. 10. This thread and forum is just for sharing knowledge between
    users. If this has affected you then you need to fill in the apple
    feedback page with your confirmed symptoms and the impact if you want anything
    to be done. Follow this link and do it now or apple pop users will remain
    without a fix! I recommend do one for each type of iOS device you have
    affected and the mail app itself.

http://www.apple.com/feedback/

Here are the other apple forum threads related to this issue -
maybe someone else is familiar with a clever way to link them all up - please
do so if you know how:

https://discussions.apple.com/thread/7226924

https://discussions.apple.com/thread/7221489

https://discussions.apple.com/thread/7226501

.

John7337 wrote:

So much for pre-release software testing!

It was tested by roughly 1 million users for 4 months. Plus an unknown number who installed the beta versions without being part of the testing program. So either none of those million used POP email, which is unlikely, or it is an isolated problem affecting only a few users. That's actually pretty likely based on how few different users have reported it (I've only been able to find under 100 unique usernames (~50 in this thread) reporting the problem out of roughly 200 million users who have upgraded so far).

I just received an email from an Apple Tech in response to CHAT over the weekend. They want screen shots of my email settings, etc. Nothing about memory. In other words, I don't think they have a clue. My suggestion is that anyone with media contacts forward this thread with its now 18,000+ views. Perhaps if we can't get Apple's attention, some critical media articles will.

Lawrence Finch wrote:

I just sent additional large email attachments totaling over 100 MB. My total mail storage is currently 273 MB. I'll keep monitoring.

Please let me know where on the phone to find the mail storage. Thanks.

.

Send the attachments "from" your POP account email on your mobile device, and monitor those "sent" msgs in your "Sent" folder for the next 24 hrs. This bug seems to be happening more frequently in my "Sent" msgs folder on my iPad than in my inbox.

Settings/General/Storage & iCloud Usage - Manage Storage

I just want to point out that this porblem is not only affecting people with POP email accounts. Both of mine or IMAP and I'm having it too.

Thank you. I'm using a 16GB iPhone 4S

Storage: Used 4.2GB Available 8.1GB

iCloud

Total Storage 5.0GB Available 2.1GB

Interested to hear whether you expect there is an issue related to memory or it's a hiccup in the mail app.

It will also tell you how much storage each app uses.

In all fairness, this thread is very hard to find and difficult to post unless one is experienced in dealing with product issues. I suspect that most do not even know these support communities exist. Further, we don't know what feedback apple received from the testers, how it responded, or how many reports were made the general ios9 release.

Lawrence Finch wrote:

It will also tell you how much storage each app uses.

Thank you. I see that Mail is using 13.6 MB.

I received an email w/photo at 6PM EDT (NYC) yesterday that I left in the Inbox. The message and attached file still open which is the first time that mail has remained after 18 hours. I will monitor this with fingers crossed.

I totally agree with you. Some people on this thread think they know the issue, some are refusing to acknowledge an issue even exists with Apple, which is very disheartening/alarming, while others are not as knowledgeable as I thought they were with regards to their mobile devices. This thread is going in circles...Some are just finally realizing things that others arrived/concluded a week ago (memory allocation issues, etc.). Some of us are not even aware that the only way this bug is going to be resolved is thru APPLE! They think the answer is going to come from this discussion or speaking to users who seem more knowledgeable or have more credentials than others. Follow and choose to believe who you want for the answers, but IMO, the answer to this bug will need to come from Apple....and yes, I am acknowledging this as a bug. A big bug! No reason to protect Apple here! They are at fault...Big time!!

Having just spent an agonising 20 mins on the phone yet again with a senior adviser, I just do not believe there is any recognition from Apple that there is even an issue. He yet again lectured me for 5 mins on the benefits of IMAP over Pop, he then blamed my isp (BT in the Uk) only for me to point out that my iPhone which is still running IOS 8 is working fine with POP mail. My isp also ensures me that BTMAIL is fully compatable with POp settings. As a short term fixed , I have reset my desktop mail program to only delete emails from the server once deleted from the inbox, however this does not solve the sent mail issue. I had also set up a imap account on my program, so all sent mails were stored in the IMAP program and synced with server. However, the senior advisor then told me that this was the probable cause of the issue, and advised me to delete the imap settings! Like everyone, I too have the memory issue, with the memorry rising to approx 60 and 80 me before somehow reducing to 20mb. Prior to IOS 9 mymail memory was pros 500 mb. All in all the advisor was absolutely no help, and did not even seem to have a grasp there is an issue. I will fill in yet another feedback form and send off this evening, this will be my 10th in 2 weeks!