Email, SMS, WhatsApp or a phone call: how to choose

Use the cheapest channel you have permission to use, and move to a more expensive one only when the cheaper one has not worked. Save phone calls for customers whose value pays for the minutes. That is a cascade, and it is more useful than arguing about whether email, SMS or WhatsApp is better in general.

Which channel works well in your market depends on your customers, and I cannot tell you that from here. I can describe the structure that works wherever you are.

What channels exist, and how do they differ?

The ones most businesses can choose from are email, SMS, a messenger such as WhatsApp or Telegram, and a phone call. Push notifications and in-app messages exist if you have an app.

They differ in three ways that matter for retention:

• Cost per contact. Email is cheap. SMS and messengers cost more per message. A call costs the most, because it takes a person's time.
• Permission. You need the customer's consent for each channel, and consent for one channel is not consent for another.
• How personal it feels. Email is low-touch. A message in a messenger feels more direct. A call is the most personal.

What is a cheapest-first cascade?

You reach the customer first by the cheapest channel that works for them. If nothing happens within a sensible time, you move up one step.

The logic is about money. If an email brings someone back, there is no reason to pay for a text. If it does not, a more expensive step may be justified, but only when the customer is worth it. Value decides how far up the ladder a customer is allowed to go. A customer who spends little gets email and maybe one text. A customer who is among your top tenth gets a call.

I describe how this works inside a casino retention system in choosing channels for casino retention. The industry is specific, the money logic is general.

Who should get a call?

Customers whose expected value covers the cost of the minutes. In practice that is the early top customers and the high-value regulars who are cooling off. For them a call is both the most effective and the most affordable use of time. A team that calls everyone burns its day for little.

If you do make calls, check their quality. A call script read badly does more harm than none. I wrote about scoring calls in how to score every call in a casino call centre; the idea of reviewing every call, not a handful, applies to a three-person shop too.

How does permission shape the plan?

It decides which channels you may use at all, customer by customer. A customer may have agreed to email and not to text messages. Check permission at the moment of sending, not only when you build the list, because the state can change.

Anyone who asked you to stop must be left out of promotional contact in every channel. Rules differ by country and by channel, and I am not a lawyer. Ask whoever advises you which channels are open to you in each market, and treat the answer as a hard input to the plan.

How often is too often?

Agree a limit on contacts per customer per week across all channels, and make every message respect it. A customer who gets an email, a text and a call on the same day does not feel looked after. They feel hunted.

If two reasons to contact a customer collide, say a reminder and a birthday offer, the more valuable one wins and the other waits. Someone has to own that rule, which is one more reason to name the person who owns returning customers, as I describe in who owns the customer after the first sale.

How do you pick the time?

Use the customer's own pattern. A message sent after the same wait to everyone often arrives when the person has already left or already come back alone. If you cannot do it per customer, a simple approximation helps: look at the days and hours when this customer usually buys or books, and aim for the hour before.

A customer who always orders on Friday evening gets nothing from a Tuesday morning message. It is noise, and noise teaches people to ignore you.

How do you know a channel works?

Do not judge a channel by opens or clicks. Measure the outcome you care about, such as returning customers and revenue per customer, and compare with a group you did not contact. A channel with many opens and no extra orders is entertainment and brings no retention. The method is in how to know a campaign worked.

Compare channels against each other for the same type of customer. A channel can look strong only because you use it for your most valuable customers.

What is a simple channel plan to start with?

1. List the channels you hold permission for, and what share of customers each one covers.
2. Rank them by cost per contact.
3. Set a rule for who may reach each step, based on value.
4. Add a stop rule for do-not-contact customers, checked at send time.
5. Run one campaign with a group left out to confirm the cascade pays.

What can you do today?

Do step 1 and step 2 on a piece of paper. Write the channels you can use, how many customers each reaches, and what a contact costs you in money or minutes.

Then pick the ten customers you most want back and decide the highest step each of them deserves. For most of them it will be a call. Make two of those calls this week.