Glossary
24-hour messaging window
The 24-hour messaging window is the time in which a professional account may message a person through Meta's API after that person messaged it. For most actions it lasts 24 hours from the person's message. Outside it, an app cannot send messages unless the human agent tag applies.
What opens the window
Meta's messaging guide says conversations only begin when an Instagram user sends a message to the professional account, for example a DM, a reply to a story or a reply to an earlier message. A comment on its own does not open the window. It allows one private reply instead, and only if the person answers that reply can more messages follow, within 24 hours of their answer.
Exceptions
When someone sends their first message after clicking a Click-to-Direct ad, Meta says the window may last up to 7 days from that message. When a human agent needs more time, the app can tag the response to use a separate 7-day Human Agent window, which is meant for people answering, not for automation.
What it means in practice
An automation that wants to send more than one message, such as a link followed by a request for an email address, needs the person to reply first. A short question in the first message, or a quick reply button that sends the person's tap as a message, does that. Messages queued for later should be checked against the window before they go out, because a message after it closes is rejected.
For how this fits into the whole flow from comment to DM, read How comment-to-DM automation works.
Sources
- Meta for Developers: Instagram API with Instagram Login: Send Messages
- Meta for Developers: Instagram Platform overview
- Meta for Developers: Send a Private Reply to a Commenter
Checked against Meta's documentation on 2026-10-20. Meta changes its rules from time to time, so its pages are the final word.
