I have a customer who runs 2012.2 and has what we think was this issue which occurred in the following order.
Got an email. Opened and clicked reply. Put in CC and BCC addresses and then moved the original message from his inbox to a shared folder in his cabinet. When he hit send he gets a D107. Upon investigation we see all messages stored in shared mailboxes (he is a person being shared with, not the original sharer) are being stored as posted messages and you can't reply directly from them (Problem1). Once we worked that out, we moved the item from said shared folder back to inbox, now we can hit reply and add cc and bcc, but when we hit send there is about a 30 second delay and then d107 again (problem 2).
Any ideas as to the cause of two said issues and resolution?
He runs W7 x64