Email has an average open rate of 30-40%. SMS hovers around 90%. WhatsApp, however, reaches 98%. Almost all your messages are read, often within minutes of being sent. This single figure encapsulates why WhatsApp marketing is becoming an essential channel for e-commerce brands.
But be careful: this proximity is also what makes it a channel to be handled with care. One too many messages, a tone too commercial, and your customers will block you. This guide explains what WhatsApp marketing is, why it's relevant for e-commerce, how to properly collect opt-ins, and how to implement it practically.
WhatsApp marketing: definition
WhatsApp marketing refers to the use of WhatsApp as a marketing communication channel between a business and its customers. Specifically, it allows businesses to send personalized messages, transactional notifications, targeted promotions, and service messages directly to the messaging app that customers use daily to talk to family and friends.
This is its main strength and peculiarity. WhatsApp is not an advertising channel. It's a conversational channel. Customers expect direct, useful, and personalized exchanges, not disguised newsletters.
In 2025, WhatsApp has 3 billion active users worldwide, including 24 million daily unique visitors in France. It is the second most used social platform after Facebook. And unlike social networks whose organic reach is collapsing, WhatsApp guarantees that your messages arrive directly in the inbox of each contact.
WhatsApp Business vs WhatsApp Business API: two very different tools
Before going further, an essential distinction.
WhatsApp Business is the free application available on smartphones. It allows you to create a professional profile, send messages to broadcast lists, and set up simple automatic replies. The limitation is significant: you can only broadcast to 256 contacts at a time, automation is very basic, and there is no access to detailed analytics. It is a tool suitable for very small businesses just starting out.
WhatsApp Business API is a completely different matter. It is the interface that allows businesses to send messages at scale, automate complex customer journeys, integrate WhatsApp with their CRM or e-commerce platform, and track precise performance. It is accessible through Meta's partner platforms such as Klaviyo, Brevo, or other specialized tools.
For an e-commerce brand that wants to use WhatsApp as a true marketing channel, the API is essential. Without it, you are limited to manual use that cannot scale.
Regarding pricing: since 2025, Meta charges per delivered message according to three categories. Marketing messages (promotions, cart reminders, recommendations), transactional messages (order confirmations, delivery tracking), and authentication messages (identity verification, one-time passwords). Prices vary by country and category.
Why WhatsApp marketing is particularly relevant in e-commerce
Email and SMS have their place. WhatsApp complements them, it doesn't replace them. Here's what it brings specifically to an e-commerce strategy.
An unparalleled open rate. 98% of WhatsApp messages are read, often within minutes of being sent. For urgent messages like abandoned cart reminders or stock alerts, this is a considerable advantage.
A rich and interactive format. WhatsApp allows you to send images, videos, product carousels, call-to-action buttons, and clickable links. This is far beyond an SMS. An abandoned cart reminder with a product photo and a "Complete my order" button is much more engaging than a standard email.
A pre-existing relationship of trust. Users instinctively trust what comes through WhatsApp because it is their personal communication space. A message in WhatsApp is perceived as more human and direct than a commercial email.
Two-way conversation. Unlike email, WhatsApp allows for real-time exchanges. A customer can ask a question, get an answer (automated or human), and finalize a purchase in the same conversation. This is a major advantage for customer service and conversion.
Omnichannel integration. On Klaviyo, for example, WhatsApp works with the same logic as email and SMS: it relies on the same customer data and segments. If a customer opens an email, clicks on a product but doesn't buy, you can send them a WhatsApp reminder a few hours later. The two channels reinforce each other.
The most effective WhatsApp use cases in e-commerce
Abandoned cart recovery is probably the most powerful use case. A WhatsApp message with a photo of the abandoned products and a "Resume my order" button grabs attention much better than an email in an overloaded inbox.
Order and delivery notifications are highly appreciated by customers. Order confirmation, tracking number, imminent delivery alert: these transactional messages have open rates close to 100% and strengthen post-purchase satisfaction.
Back-in-stock alerts allow you to recover customers interested in an out-of-stock product. A WhatsApp message when the product is back in stock generates an almost immediate conversion.
Exclusive offers and VIP access work very well for loyal customers. Early access to sales, a promotion reserved for WhatsApp subscribers, or an invitation to an event creates a strong sense of belonging.
Conversational customer support allows you to manage returns, questions, and complaints directly in WhatsApp, with the complete customer relationship history accessible at each exchange.
WhatsApp opt-in: the most important rule
This is the point on which there must be no compromise. WhatsApp requires explicit consent before sending any marketing message. This is not just good practice, it's a legal obligation. Sending messages to contacts who have not given their consent exposes you to account blocking by Meta, and potentially to GDPR sanctions.
A valid WhatsApp opt-in means a person has explicitly agreed to receive messages from your brand via WhatsApp, with clear information on what they will receive and the ability to unsubscribe at any time.
Specifically, the main ways to collect WhatsApp opt-ins are:
Via your e-commerce site, with a dedicated checkbox during account creation or checkout. The wording must be clear: "Receive my order confirmations and exclusive offers on WhatsApp".
Via a pop-up form or a dedicated landing page, with a phone number field and an explicit opt-in checkbox.
Via a QR code on packaging or at a physical point of sale, which links to a WhatsApp registration conversation.
Via "Click to WhatsApp" ads on Facebook and Instagram, which allow initiating a conversation directly from an ad and collecting the opt-in within the conversation.
Via your email or SMS welcome flow, by inviting your subscribers to also sign up on WhatsApp to receive exclusive offers.
In all cases, keep a record of each opt-in, including the date, channel, and exact wording presented at the time of subscription.
How to practically implement WhatsApp marketing
Step 1: choose your platform.
For an e-commerce store on Shopify or WooCommerce, Klaviyo offers native WhatsApp integration that leverages the same customer data as your email and SMS flows. Brevo also offers an accessible WhatsApp marketing solution, well-suited for very small businesses and SMEs.
Step 2: create and validate your templates.
On WhatsApp Business API, marketing messages must be pre-approved by Meta as templates. These templates define the message structure, with personalization fields (first name, product, order link, etc.). Validation usually takes a few hours to a few days. Templates rejected for overly promotional content must be rephrased and resubmitted.
Step 3: build your automated flows.
Start with the flows with the highest potential: abandoned cart, order notifications, and back-in-stock alerts. These are the easiest use cases to implement and those that generate the quickest ROI.
Step 4: define your sending frequency.
This is crucial. WhatsApp is an intimate channel. Excessive frequency will quickly destroy the relationship. The general recommendation: no more than one to two marketing messages per week. Transactional messages, however, are sent on demand according to customer actions and do not pose a frequency problem.
Step 5: set up a simple opt-out.
Every message must include a clear unsubscribe option. "Reply STOP to stop receiving our messages" or an unsubscribe button directly integrated into the message. This is a legal obligation and good practice that protects your reputation.
Golden rules for successful WhatsApp marketing
WhatsApp is a conversational channel, not a broadcast channel. Every message must provide real value: useful information, a relevant offer, a concrete benefit. A generic message that looks like spam will destroy the trust you took time to build.
Always personalize. The first name, the product concerned, the context of the exchange: the more precise the message, the more engaging it is.
Do not replace email and SMS with WhatsApp. Add it to your omnichannel strategy by leveraging what it does better than other channels: immediacy, rich format, and two-way conversation.
What The Modern Letter does with WhatsApp
At The Modern Letter, we integrate WhatsApp into our e-commerce clients' CRM strategies in addition to email and SMS on Klaviyo. API configuration, template creation and validation, automated flow building, opt-in collection, and performance monitoring: we manage the entire deployment so that WhatsApp becomes a real revenue channel, and not just an experiment.
Because a well-placed message on WhatsApp, at the right time and with the right content, can do what email can no longer do: capture the immediate attention of a customer who had decided not to buy.
