Save the PPS to the desktop. (You can save it anywhere but the desktop is the quickest)
Now Right Click and Get Info on the file.
Expand out the Get Info window, specifically the Open with: section.
Using the dropdown menu, the little arrows on the end of the Open with field, Choose Keynote to open that file with.
If Keynote is not available, choose Other and browse to the Applications folder and find Keynote there.
Once done, click the button that is underneath the line "Use this application to open all documents like this one."
The button says "Change All"
Close the Get Info window
That should do it for you
P
I have a 20 inch early 2009 iMac. I was running Snow Leopard and made the mistake of upgrading to Yosemity (Apple site told me my iMac could handle it) but this was a BIG mistake. I reverted back to Snow Leopard and am NOW running Mountain Lion (10.8.5) since Snow Leopard was no longer supported.
My question how do I get a PPS attachment in mail to automatically open with Keynote. Right now I have to control-click every time and do the "open with". In Snow Leopard I only had to click the attachment and Keynote would open without having to direct every time.

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