aliensporebomb:
I am having similar problems on my iPhone 6. In my situation multi-page .pdf attachments display only the first page as an image in Mail rather than the traditional PDF icon attachment at the end of the email.
I did not have any of the offending third-party apps listed in the posts to delete, but had some other well-respected apps (Evernote, WebEx, etc.) that would appear in the past when the "Share" sheet or tab was activated after a long click on a PDF file. I deleted those apps, but no relief.
So far I have tried the following WITHOUT success:
-Hard reboot (Hold power and home buttons for 15-20 seconds and watch the Apple logo do its thing).
-Restore iPhone from iTunes Backup.
-Delete some of the Apps that use the Share sheet (e.g., Evernote, WebEx, etc.) and hard reboot.
-Uninstall the email accounts; hard reboot; and reinstall the email accounts.
-Update from iOS 9.2.1 to iOS 9.3.2.
I keeping wondering if the email type changed on my Exchange server as you elude to in your post.
Did you ever find any connection between Exchange settings and this issue?
Thanks.