How to use email attachments in Mail for iPhone and iPad
We've been wishing for better file attachments in Mail for years and with iOS 9, Apple has delivered. No longer do you have to go to an app and share a file from there. For security reasons, you still can't go wandering through the file system, but now you attach any file from any storage provider app, including iCloud, Dropbox, Google Drive, OneDrive, and more. And, when you get an email attachment, you can now save it out to your preferred storage provider as well.
Full story from the iMore Blog...