I have a problem, partially resolved in new 6.0.1 version, when I share a folder, and I send the notification message to all my address, I often see that the mail they received don't have "Accept" or "Decline" botton. We all use web client.
(I see the new "sharing utility" in preferences that permit to look up if a user share to my contact any resource but is better, with some kind of user, send message...)