Yeah, same here.  Lots of useless suggestions from Quickbooks support.  It's something in the program that they need to fix and who knows when that will happen.  The best workaround posted so far is to save the email, close it in both Outlook and Quickbooks and then reopen the saved email and make necessary edits and send to customer.  I'm not holding my breath that they will fix this any time soon, just grateful there is a workaround that isn't too difficult and does what I need it to do.  Good luck to you.