Why can't I reply to a Facebook message in Inbox?
Facebook’s Messenger Platform Policy provides the following reasons for receiving the error message Unable to send Facebook message when replying to a Facebook message in Inbox:
- The Facebook user left a comment on your Page or sent you a private message, and you did not reply within 7 days of the user's most recent communication.
- The Facebook user blocked or muted your conversation.
For more information, see Facebook’s Messenger Platform Policy Overview.