Rate limits for the Messenger Platform depend on the API used and, in some cases, the message content.
Requests made by your app are counted against the number of calls your app can make in a rolling 24-hour period, calculated as follows:
Calls within 24 hours = 200 * Number of Engaged Users
The Number of Engaged Users is the number of people the business can message through Messenger.
Requests made by your app are counted against the number of calls your app can make per Instagram Professional account and the API used.
If your app user's Page or Instagram Professional account sends or receives a high volume of messages, the inbox can no longer display or send new messages until the volume decreases.
If a Page sends more than 40 messages per second or constantly sends or receives messages in a large number of conversations at the same time, new messages are not displayed in the Page Inbox and the Page cannot send new messages until the volume decreases.
If a Page hits the high-volume limit, API calls to get all conversations fail. You can still call a single conversation to get new messages for that conversation.
If an Instagram Professional account sends and receives more than 72,000 messages, new messages are not displayed in the Instagram Inbox and the account cannot send new messages until the volume decreases.
Banners are displayed in the conversation indicating the limit has been reached. These banners stop showing when the message volume decreases.