Why can't I reply to a Facebook message in Inbox?

You might receive the following error message when you try to reply to a Facebook message:

Unable to send Facebook message

Facebook’s Messenger Platform Policy gives the following reasons for this message:

• It has been more than 7 days since the last message was received from the user. Facebook does not allow replies after 7 days.
• The Facebook user blocked or muted your conversation.

For more information, see Facebook’s Messenger Platform Policy Overview.