The WhatsApp 24-hour window

Almost everything that looks strange about WhatsApp at work comes from one rule, and it is not a Lynomia Chat rule. It is WhatsApp's.

When a customer messages you, you can write back freely for 24 hours. After that, the only thing that will send is an approved template.

That is the whole rule. Templates, campaigns, automation and most of this section exist because of it.

Why WhatsApp has it

WhatsApp is the app people keep for family. Meta protects that by making the customer's own message the permission slip: a business may talk freely to someone who has just spoken to it, and otherwise may only send message shapes it has reviewed in advance. Breaking it is not possible — the message simply does not go out.

How the clock actually runs

The clock starts at the customer's most recent message in that conversation.
It runs for 24 hours and is per conversation. One customer being inside the window tells you nothing about another.
Nothing you send restarts it. Not a reply, not a template, not a campaign. Only a new message from the customer does.
A customer who messages you at 09:00 and again at 20:00 has pushed the deadline to 20:00 the next day.

What changes when it closes

	Window open	Window closed
Typing a reply in the conversation	yes, anything	the composer is switched off
Images, files, voice notes	yes	no
An approved WhatsApp template	yes	yes — the only thing that sends
A WhatsApp campaign	yes	yes, it sends a template
An automation rule that sends a message	yes	the message is created and then fails
A satisfaction survey	yes	not sent
A private note	yes	yes — notes are never sent to the customer

When the window is closed, the reply box tells you so: you can only reply using a template message due to 24-hour message window restriction. Use the WhatsApp templates button beside the composer and pick an approved template.

If something sends a plain message anyway — an automation rule, a flow, your own integration — that message does not quietly vanish. It appears in the conversation marked Failed to send, with WhatsApp's own explanation underneath: the 24-hour customer service window is closed and no template was used.

A worked example

A customer asks about a delivery at 11:00 on Sunday. Your agent replies, they talk, the conversation is resolved at 11:20.

Sunday 18:00 — you remember something. The window is open until Monday 11:00, so you type it and send it.
Monday 15:00 — the courier updates you. The window closed four hours ago. Typing is no longer possible. You send your approved order_delivered template instead, and the customer's reply to it opens a fresh 24 hours.
Tuesday — you want to tell 400 customers about a sale. Most are long outside the window, which is why a WhatsApp campaign sends a template rather than a message you type.

What this means for how you work

Answer inside the window. It is free-form, it is immediate, and it costs you nothing in review cycles.
Prepare templates before you need them. The moment you need one is the moment you cannot write one — approval is WhatsApp's and takes as long as it takes. See WhatsApp templates.
Do not build your process around reopening the window. There is no way to reopen it from your side.

Limits

The window cannot be extended, shortened or switched off. It is not a setting anywhere in Lynomia Chat.
A template is not unlimited either. Meta caps how many unique customers you may message outside the window in a rolling 24 hours — your business messaging limit. It is shown on the inbox's Account Health tab, Meta decides it, and it is shared by every WhatsApp number in the business portfolio.
Lynomia Chat does not warn you that the window is about to close. There is no countdown and no reminder.
Other channels have their own windows, and they are not the same number. A WhatsApp number running through Twilio has the same 24 hours; Facebook, Instagram and TikTok differ.
Resolving or reopening a conversation changes nothing. The window only ever follows the customer's last message.

If it does not work

The composer is greyed out on a conversation I am sure is recent. Check the last incoming message, not the last message. Your own replies do not count.

The template button shows nothing. The inbox has no approved templates synced yet. See WhatsApp templates.

My automation replies keep failing. The rule fires on something that happens long after the customer wrote — hours later, or on a resolve. Have it send a template, or have it fire on the incoming message instead.