If you send the message via Contact Form and get in response “message body empty” –
Most likely the problem is in that you have removed all data from Message field in Submit Options. This Message field contains information which you will receive on email from users. You can edit this field as you want, but it should contain this variable (required) – [form_data] , where form_data – is the user data from your contact form. Therefore in order to fix the problem – you need to add [form_data] variable to the Message field.