Send smarter: Your WhatsApp best practices guide  

WhatsApp is the most popular messaging channel globally, with over 2 billion users and 98% open rates (compared to email's 20%). With numbers like that, it's no surprise you've added WhatsApp to your tech stack.

However, you quickly see that WhatsApp is not like SMS or email. It’s an entirely new channel with its own playbook and best practices.

Meta, the parent company of WhatsApp, actively enforces strict quality standards, and a single poorly executed campaign can result in account restrictions. One bad send, and you could lose your ability to message customers entirely.

But the good news is that we're here to help. Whether it's your first time sending WhatsApp through Customer.io or you're looking to refine your approach, follow these best practices to build a high-performing WhatsApp program that delivers results without risking your sending privileges.

Learn more about sending WhatsApp through Customer.io.

You cannot send WhatsApp messages to anyone who hasn't explicitly opted in to receive messages from you via WhatsApp specifically. For WhatsApp, opt-in is mandatory.

What counts as a valid opt-in:

• A checkbox specifically for WhatsApp (separate from email or SMS)
• Clear language like "Receive order updates via WhatsApp"
• Setting expectations about message types and frequency

What doesn't count:

• Auto-enrolling your email or SMS subscribers
• Using "implied consent" because someone is a customer
• Vague "marketing communications" opt-in without mentioning WhatsApp

Those who didn't explicitly opt in may block you immediately. Those blocks negatively impact your quality rating, which can result in the restriction or suspension of your account. You must build your WhatsApp list effectively from the start.

What to do now: Do you have proper opt-in in place? Add a WhatsApp-specific checkbox to your signup forms with clear language. Don't auto-enroll your existing email list; instead, invite them to opt in.

Meta assigns a quality rating to every WhatsApp Business number, categorized as high, medium, or low, based on how users respond to your messages. This rating directly impacts and controls your ability to send. The better your rating, i.e. if your business maintains a Green quality rating, you can become eligible for more features.

The levels:

• High (green): High quality.
• Medium (yellow): Medium quality.
• Low (red): Low quality.

If you send to people who didn’t opt in, send irrelevant or low-value content, message too frequently, people block you, or use poor segmentation, you risk lowering your quality rating.

What to do now: Check your quality rating in Meta Business Manager and set a reminder to review it for your first month of sending.

Unlike SMS, WhatsApp doesn't allow you to send free-form messages whenever you prefer. When you initiate contact with a customer, you must use a pre-approved message template.

How templates work:

• Create message formats with placeholders in Meta's template builder within WhatsApp Manager: "Hi {{1}}, your order {{2}} has shipped!"
• Submit them to Meta for approval (typically 24-48 hours)
• Once approved, you can use them in your Customer.io campaigns

Template categories matter. There are three categories:

• Utility: Transactional updates only (order confirmations, shipping notifications, appointment reminders). No promotional language allowed.
• Authentication: Security codes, 2FA, verification only.
• Marketing: Promotional content (sales, offers, product launches). Cannot be sent to US recipients as of April 2025.

Avoid sneaking promotional content into Utility templates. Meta will likely reject them. Keep your messages clearly defined to avoid penalties.

What to do now: Use Meta's template builder in WhatsApp Manager to draft your 3-5 most important message templates (order confirmation, shipping update, etc.). Submit them to Meta for approval, and wait for Meta's green light before you start building campaigns.

When you first start sending WhatsApp for business, your account can message only a limited number of customers per 24-hours. That number starts usually at a limit of 250 and you can scale upward from there. Note that these limits mainly apply to business-initiated messages (i.e., when you, the business/company, reach out first). As you demonstrate that you are a high-quality sender (with well-received messages, no spam, and opted-in users), WhatsApp will increase your limit.

To scale safely, start by messaging your most engaged customers. Then, increase volume slowly over time. WhatsApp will reward your good sending habits!

What to do now: Send your first campaign to your most engaged 100+ customers, watch how it performs, then gradually increase volume.

Want to know the fastest way to ruin your quality rating? Send generic messages to everyone on your list. Not everyone wants the same type of content. Keep your messages relevant and personal.

Some tips:

• Send transactional updates only to people who made a purchase
• Send promotional messages only to users who opted in for marketing specifically
• Personalize based on past behavior, preferences, and engagement history
• When in doubt, send to fewer people with a more targeted message

A good rule of thumb is that you can't explain why a specific person or group should receive a specific message…then don't send it.

What to do now: Create 2-3 WhatsApp-specific segments in Customer.io. Before hitting send, make sure you can explain in one sentence why this group needs this message.

High open rates on WhatsApp mean users will definitely see your messages, but the flip side is that this also means they will notice if you're messaging too often.

Frequency guidelines:

• Transactional messages: As needed (order updates, shipping notifications, appointment reminders)
• Promotional messages: Maximum 1-2 per week for most audiences; reserve higher frequency only for VIPs who explicitly want it
• Timezone awareness: Always send during reasonable hours in the recipient's timezone

What to do now: Set a frequency cap, for example: "Max 2 marketing messages per month.” Then, build it into your Customer.io campaigns using frequency limits or suppression rules.

WhatsApp isn't email, SMS, or push. It's a personal communication space where many people chat with friends and family. Your messages appear right alongside those conversations, which means the bar for relevance and value is much, much higher.

Before sending, ask yourself:

• Would I personally want to receive this message?
• Is this timely, relevant, and useful to this specific recipient?
• Does this message provide clear value (save time, save money, solve a problem)?

Examples of valuable messages:

• "Your package arrives today between 2-4pm" (timely, actionable)
• "The shoes you viewed are back in your size—20% off today" (personalized, relevant)
• "Your appointment is tomorrow at 10am. Reply to confirm or reschedule." (useful, convenient)

A low-value message, such as something generic like “BIG SALE!” with no personalization, is not valuable to most customers.

What to do now: Before launching, ask yourself (or a teammate): "Would I actually want to receive this?" If the answer is "maybe," keep refining.

There is a strict list of content that's banned on WhatsApp, regardless of whether it's legal in your country.

Prohibited content includes:

• Illegal activities or goods
• Adult content or sexual services
• Real money gambling
• Firearms, weapons, ammunition
• Illicit drugs or drug paraphernalia
• Hate speech, violence, discrimination
• Tobacco and vaping products (in most cases)
• Sending Marketing templates to US-based WhatsApp recipients. Utility and Authentication messages are still allowed for US users.

Violating these policies may result in the suspension of your account. When in doubt — don't send it.

What to do now: Review Meta's prohibited content list and double-check that none of your planned messages fall into banned categories. When in doubt, don't send it.

If you're following best practices, you should see:

• Quality rating consistently High
• Block rate under 0.5%
• Delivery rate above 95%

And, of course, you should see strong engagement, such as high open rates, clicks, and replies.

WhatsApp rewards quality over quantity, relevance over reach, and patience over speed. Despite its strict quality standards, WhatsApp is not only the most widely used messaging channel in the world; it’s #1. With billions of users, tapping into this channel could become one of your most effective customer engagement channels.

Ready to add WhatsApp to your multi-channel marketing strategy? Customer.io now natively supports WhatsApp. Start sending WhatsApp today!