SMS, e-mail or WhatsApp for customer notices: which channel for each message

The short answer: use SMS for anything that is short, important and must reach any mobile phone, even without internet or apps: reminders, codes, order notices, alerts. Use e-mail for anything long or with documents, such as a PDF invoice. Use WhatsApp to chat with people who already talk to you there. Often the best answer is two together: a short SMS that alerts and an e-mail with the details.

The general comparison of the three channels, with pros, risks and who each suits, is in WhatsApp, e-mail or SMS. Here we go message by message.

Message by message

The message	Channel	Why
Appointment, meeting or booking reminder	SMS	Short, read on the day, and it reaches people with no mobile data
Verification code	SMS, through the API	Reaches any phone, even without internet or apps
Order or delivery notice	SMS, plus e-mail for the details	The SMS says “it is ready”; the e-mail carries the item list
Payment reminder	Short SMS, invoice by e-mail	The SMS flags the date; the document goes by e-mail
Invoice, receipt or contract	E-mail	Carries the attachment and stays on record
Promotion or campaign	SMS or e-mail, only to people who agreed	SMS for a short, time-limited offer; e-mail for a catalogue
Replying to a customer	WhatsApp, e-mail or phone	An SMS sent under a name cannot receive replies
Urgent alert (new opening hours, closure, a service outage)	SMS	Reaches everyone, even without internet
Long news, monthly updates	E-mail	Room for the full text, images and links

Example SMS, ready to adapt

Use	The SMS
Reminder	Hello Carlos, a reminder that your appointment is tomorrow at 9:30. To rebook, please call the clinic.
Order	Your order No. 4521 is out for delivery today. Collection code: 7731.
School	Dear parent, the parents’ meeting is on Friday at 5pm, in room 3.
Payment	Hello Paulo, your invoice is due on Friday. We have sent the document to your e-mail.
Customer reply	Hello Ana, your request is ready. Questions: call [PHONE] or write to [E-MAIL].

Notice the last two: the SMS points to another channel. That is how you combine the strengths of each. More service-notice examples in transactional SMS, and collection examples in payment reminder SMS.

Three rules for every channel

1	Say who is sending. Put your company name in the text, even with a Sender ID.

2	Do not expect replies by SMS. Neither the free NETMSG sender nor a Sender ID can receive replies. Write a phone number, an e-mail address or your website in the message.

3	Send only to people who agreed to receive messages, and keep service notices apart from promotions. See SMS good practices and consent.

SMS is paid per part. Each part uses 1 credit, between $0.0092 and $0.0167 depending on the price tier, and long text, or text with Portuguese accents, splits into more parts. Anything that needs many lines is better by e-mail; the SMS says what matters and points there.

When in doubt, ask: if the customer does not see this message today, do they lose something (an appointment, a delivery, a deadline)? If yes, it is an SMS. If it can wait, or needs a document, it is an e-mail.

Want to use SMS for your most important notices? See the prices and start with the free sender.

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