Facebook offers a choice of three types of messages that can be used in different situations to send messages to people who subscribe to your chatbot on Facebook Messenger.
Your chatbot may send one message within 24 hours of a person sending you a message or opting-in to receive messages via a web plug-in on your website (e.g. Maisie’s Abandoned Cart Rescue plug-in). After the 24-hour time limit has expired you may send only one additional message unless the person messages you back in which case the counter resets. There are exceptions to this rule for notification type messages like order and shipping updates, event reminders, payment & account updates, etc.
Your chatbot is permitted to send messages any time but these messages must not be promotional in nature. This type of message is intended for sending news and information (e.g. new blog posts) and reminders.
A Facebook ad in the form of a standard message (but marked ‘Sponsored’) that can be sent to all, or a segment of, people who have open conversations with your bot. Facebook charges an advertising cost for sending these messages but they can be a very effective investment to re-engage inactive Messenger subscribers.