On the Mac, the key combination would be Shift-Cmd-X (for all recent versions of Acrobat Pro). This will NOT work with Acrobat Standard. You can also open the Print Production tools and execute Preflight from there. To add it to your toolbar by right-clicking on the Preflight tool and select "Add to quick tools toolbar" (only Acrobat XI, DC does not not support this simple method anymore). In Acrobat DC (this also works in earlier versions), you right-click on the gray background of your toolbar and select to "Customize Quick Tools", then navigate to the Print Production and select the Preflight tool.
Karl Heinz Kremer
PDF Acrobatics Without a Net
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