"...not downloaded from the server." ???

I can only tell you my experience with the same problem using Comcast and Outlook. Because the email is downloaded to my desktop at the same time as my iphone, I get the same message. All I did was go to Outlook on my desktop to: Tools/email accounts/view or change existing email account/next/change/more settings/advanced/delivery/*remove from server after _ days. By extending the days, the email/attachment stays on the server and therefore opens on my iphone. I did this a few days ago and it seems to be working. Good luck!