In Apple Mail, when attaching a file from local folders using drag-and-drop, most of the time the attached file (not the original in the folder) is corrupted and cannot be opened by email recipient or by me in Sent messages.
what happens when you try to open the file? Do you get error dialog or message? Does it simply not open.. as some application trys to launch but does not? More details... or is there no point in providing details?
I understood you proposed this as a workflow. When I move the attached file from a sent message to a folder and try to open it from there, I get the same message. So it seems it gets corrupted in the Mail app.
I understand.. but you are using Beta software after all. If you plan to provide feedback to Apple, you will need to collect all these details and perhaps more. Nobody can really offer help or provide suggestions without all the details, so you are effectively shouting into a void. What's the point in that?