Why can't I message a customer on WhatsApp?

Yes, you can message customers on WhatsApp — Nassima just follows one timing rule that WhatsApp itself sets.

Open the conversation in the Inbox and reply as you normally would.

Inside the 24-hour window: You can send any free-form message, the same as on any other channel.

Outside the 24-hour window: Only a WhatsApp message template that Meta has already approved can go through.

This 24-hour window itself comes from Meta, not Nassima — Messenger and Instagram track a version of the same rule. WhatsApp is the one where it actually stops you: outside the window, a free-form message is blocked outright rather than quietly going through some other way, which is why a message can end up undelivered even though everything on your side looks right.

Setting up templates and getting them approved by Meta is covered under Message templates — build and submit your WhatsApp templates there before you need them, since approval isn't instant. For everything else about sending messages across channels, see Send messages.

Check the conversation thread itself if a message looks like it didn't land — the window is what decides whether a free-form reply goes through or needs a template instead.