In my mothers hudl, the stock email app, can't download pdfs in 3 emails. Adobe Acrobat is present. When the attachment is tapped it says "Info...No app can open this attachment for viewing". Also, in grey below the attachment filename it says: "Couldn't download. Touch to retry." Note in gmail app they download and open successfully. Sadly I've taught my mother to use the stock app, and not gmail, so trying to teach her over again isn't the solution....this should work....I'm baffled, any ideas on how to resolve???