I receive a number of ATTACHMENTS to emails which are represented by a rectangle, containing a small blue square, with question mark. About a third of these will open, but the rest do not. Can you suggest the specific programme, or facility, which I can download into my Mac to enable me to open them all. I usually download the latest Adobe help when offered, but obviously dont have the full range, or whatever I need. Thank you. R.Hoyte .In any reply please give me the full number of steps, as I am not a computer expert.