Email, SMS or WhatsApp: which one gets read?

Every service business ends up sending four kinds of message. Confirmations, reminders, follow ups and marketing. Most businesses pick one channel and use it for all four, which means three of them are being sent on the wrong one.

The channels have genuinely different properties and the right answer is to match the message to the channel rather than to have a favourite.

Email

Cheap to the point of free, unlimited length, keeps a record and handles attachments. Open rates on transactional email are strong and open rates on promotional email are not, which tells you what it is for.

Use it for confirmations, receipts, invoices, forms, anything with a document attached and anything the client may want to find again in three months. Use it for newsletters if you have something worth saying.

Do not rely on it for a reminder two hours before an appointment. A meaningful share of people will not have looked at their email in that time.

SMS

Almost universally read and read quickly, which is exactly why it should be rationed. It costs real money per message, it is short and it arrives with an urgency the recipient did not choose.

Use it for the reminder the day before, the "your car is ready" message, the running late notice and the cancellation slot offer. Anything time critical and short.

Do not use it for marketing unless the consent for that is explicit and recorded. UK rules on electronic marketing are stricter than most people assume, and a promotional text to somebody who only ever agreed to appointment reminders is the single most common compliance mistake in this market.

WhatsApp

Very high open rates, conversational, free at the point of use for the customer and increasingly the channel people actually prefer. It also has the most rules attached, because business messaging on WhatsApp runs on approved templates outside an open conversation window.

Use it where the customer has chosen it. Confirmations, reminders and the back and forth that a phone call used to handle. It is particularly good for anything with a photo attached, which makes it a natural fit for garages, groomers, valeters and trades.

The distinction that keeps you legal

A message about an appointment somebody booked is part of delivering what they asked for. You do not need marketing consent to tell somebody their appointment is tomorrow.

A message trying to sell them something is marketing, and marketing needs consent that is specific, freely given and recorded, with an easy way out in every message. A pre-ticked box is not consent and "by booking you agree to receive offers" is not consent either.

Record consent per channel, per person, with a date. If you cannot evidence when and how somebody opted in, you cannot demonstrate you had permission, and demonstrating it is your job rather than theirs. This is a summary rather than legal advice.

A sensible default set

• Booking confirmation by email, with the calendar file and any forms.
• Reminder 24 hours ahead by SMS or WhatsApp, whichever they chose.
• Short reminder on the morning where no shows are a real problem.
• Follow up two days later by email or WhatsApp.
• Marketing by email as the default, with SMS reserved for the two or three moments a year that genuinely justify the cost and the intrusion.

The cost angle nobody models

SMS looks cheap per message and is expensive at volume. Sending two reminders by text to 400 clients a month is a real line in your accounts, and half of those people would have read an email perfectly happily.

Let people choose the channel at booking, default the noisy ones to the cheap channel and reserve the expensive channel for the messages where being read within the hour is worth paying for.