Some files are not valid as attachments on the Mac

I have this problem since Beta 1… Some files are not valid as attachments in a message. In the dialog that you select the file to attach, some files appear as grayed out.

I still could not find a pattern to which files are valid or not. However, today I was able to attach one of those files by dragging it to the body of the message, instead of using the Attachment dialog, where it still appears grayed out for selection.

I tried messing with MIME settings but had no luck.

Does anyone with a Mac have this problem? Any clues?

Subject: Some “files” are really folders

Especially if you use Apple’s iWork suite (but also some other apps), the “files” you save are really packages, which are just folders with a predetermined structure. It’s possible this is what you’re seeing. The Finder knows enough about packages to display them as single entities, but you can right-click them and select “Show Package Contents” to dive into them.

Notes is not able to attach arbitrary folders, including packages. For the time being, you will have to create an archive (ZIP, tar, etc) of the package before attaching it. We’re considering adding the ability to attach folders to a document in a later release, but this won’t be available in 8.5.

Subject: I’m having some problems, but not this

No issues with any attachments so far. I use Office documents frequently, and also some images and even audio.