Open rates of 90% are real. So is the speed at which customers block a brand that abuses them.

The mechanics, briefly

Three things govern what you may send, and understanding them prevents most of the mistakes brands make.

1. Consent. You need it, explicitly, before the first message. A phone number collected at checkout is not consent to market to it. Opt-in must be clear and recorded.
2. The 24-hour service window. When a customer messages you, a window opens during which you can reply freely with normal messages. Outside it, you must use an approved template.
3. Templates. Messages sent outside the service window must use a pre-approved template, and template categories carry different rules and costs. Marketing templates are treated differently from utility ones such as order updates.

The flows worth building, in order

1. Order and delivery updates

Confirmation, dispatched, out for delivery, delivered. Highest engagement, lowest complaint rate, and they build the habit of a customer opening your messages. If you build nothing else, build these.

2. COD order confirmation

In markets with high return-to-origin rates, a confirmation step before dispatch is one of the highest-return automations available. It catches remorse and wrong addresses before they turn into logistics costs.

3. Abandoned cart recovery

Faster to be seen than email by a wide margin. One message, sent within a few hours, with the cart contents and a direct link. Not three messages, and not with a discount in the first one.

4. Replenishment reminders

For consumables, a message timed to when the product is likely running out is genuinely useful rather than promotional. Time it from your own repeat-purchase data.

5. Review requests

Sent after delivery, with a direct link. Response rates comfortably exceed email, and verified-purchase reviews are worth more than solicited ones from any source.

6. Broadcast promotions

Last on the list deliberately. They work, they are expensive, and they are what gets brands blocked. Segment tightly, cap the frequency, and treat every broadcast as spending down a balance of goodwill you cannot easily rebuild.

What gets a brand blocked

• Messaging without clear opt-in, on numbers harvested from orders
• More than about one promotional message a week to the same person
• Broadcasts to the entire list rather than to a relevant segment
• Messages with no purpose other than presence
• Sending at hours nobody wants a phone notification
• No obvious way to stop receiving messages

Watch your block and report rate as the primary health metric of the channel, ahead of open rate. Open rate will look excellent right up to the point where the list has quietly shrunk.

Measuring it honestly

WhatsApp attribution is generous by default, because the channel is high-intent and reaches people who were already close to buying. A cart recovery message sent to someone who was returning anyway will claim the sale.

• Hold out a control group — a random 10% who receive nothing — for at least a fortnight
• Compare conversion between the group that received messages and the holdout, not against a historical baseline
• Track revenue per message sent, so cost per message stays in view
• Track block rate and opt-out rate per campaign, and treat a rise as a stop signal

This applies to every lifecycle channel, but it matters most here because WhatsApp's apparent performance is so high that it discourages the question.