> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zapbip.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 24-hour window

> Why a message may be queued and what the owner receives.

WhatsApp lets zapbip send free-form messages only within 24 hours of the last message from the owner. zapbip closes its own window 10 minutes early. A reaction from the owner does not open the window.

While the window is open, messages go out at once with `delivery: "sent"`.

When it is closed:

* the tool returns `delivery: "queued"` and the message waits in the outbound queue;
* the first queued message sends the owner one approved notice, once per closed window;
* the next message from the owner opens the window and flushes the queue in order;
* queued messages older than 7 days become `expired`.

A send that the channel rejects is stored with `delivery: "failed"`, and the tool returns an error naming the kind.


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