Cannot attach files in Mail app - claims file is empty

Please follow these directions to delete the Mail "sandbox" folder.

Back up all data.

Triple-click the line below to select it:

~/Library/Containers/com.apple.mail

Right-click or control-click the highlighted line and select

Services ▹ Reveal

from the contextual menu.* A Finder window should open with a folder named "com.apple.mail" selected. If it does, move the selected folder — not just its contents — to the Desktop. Leave the Finder window open for now.

Quit and relaunch Mail, and test. If the problem is resolved, you may have to recreate some of your Mail settings. You can then delete the folder you moved and close the Finder window. If you still have the problem, quit Mail again and put the folder back where it was, overwriting the one that may have been created in its place. Post your results.

Caution: If you change any of the contents of the sandbox, but leave the folder itself in place, Mail may crash or not launch at all. Deleting the whole sandbox will cause it to be rebuilt automatically.

*If you don't see the contextual menu item, copy the selected text to the Clipboard (command-C). In the Finder, select

Go ▹ Go to Folder...

from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.

I am having exactly the same problem, I tried the above steps but the problem still persist. Do you have any other solution. I also tried to create a new user account (of the machine) and configured email in that, but still attachment attaches blank file only. Also when I try to attach through the attachment button, it does not attaches. I have tried moving the com.apple.mail folder through the contextual menu, but it not worked.

Please help.

Hade the same problem, did the ML reinstall, and it works fine now. But given the time it took to reinstall, I hope I won't have to do this often!

BTW, here's how to reinstall ML without erasing your HD, but make a copy of your files just in case!

http://support.apple.com/kb/PH10763

Linc Davis' solution unfortunatly didn't work for me. So I guess your ML reinstall option is my number, though I am a little bit concerned about my apps.

I have a very healthy backup routine, so I am not worried about files. In the other hand, is it possible that after the reinstall procedure I may have some apps not running as fine as they were before? I mean, without my personal adjustments, saved accounts and not recognizing (asking once again for) some serial numbers/licences etc?

I am quite sure I have already passed through these stumbles before. Just don't remeber with wich apps.

From another perspective: waiting for Mavericks and avoiding this kind of trouble, since I will upgrade to it anyway, would be a reasonable option?

kind regards