For several years I have been using Thunderbird to send out invoices from an old version of Peachtree under Windows Until today, each email would queue in a separate Thunderbird window, allowing me to modify the text of the email prior to sending. Today, rather than queuing the outbound emails I am getting the message "Another application is attempting to send mail using your user profile. Are you sure you want to send mail? My only choices are OK or Cancel, and there is an option to continue these warnings or not. If I choose OK the email goes out without ever displaying. If I cancel it does not go out. I am running Windows 7 Home, Thunderbird version 60.5.2 build 20190221150524. I have not changed any Thunderbird settings that I know of. How do I get back to the mode of reviewing outbound emails?