What Is Facebook Subscription Messaging?
The explanation starts with the 24+1 Facebook Messenger rule.
In the first 24 hours of a user opting in to messaging, you can send unlimited updates, promotional and non-promotional.
After 24 hours, you can send unlimited non-promotional updates and one promotional follow up. This is called the 24+1 Rule and what Facebook calls “standard messaging.”
After the 24 Hours since the last engagement you can still send non promotional messages without issue, to reset that 24 hour clock.
Once your audience member re-engages you have a new set of 24 hours to send marketing material
If you opt to NOT send a non-promotional re-engagement message you have the option to do so, via Facebook, and for a fee.
Chat Blasts (promotional messages outside the 24+1 hours) are NOT sent through Chat or Manychat. Chat Blasts are sent via Facebook Ads Sponsored Messages.