I have the same issue as stated above and have tried all of the fixes suggested and still have the same message come up - I am unable to email statements - the same msg comes up with invoices and estimates but I am able to bypass and send anyway.  Statements however are what we normally send and can not receive any payments if unable to send statements.  I have contacted QB support and keep getting the run around that they are working on it and will call me back - which they never do.  It does not seem to be understood that I can not run my business if I can not send statements.