Understanding the difference between email and SMS

You will learn

Learn how email and SMS differ as well as when to use each channel.

When to use SMS vs. email

SMS

Use a text message for time-sensitive content (e.g., a flash sale) or important updates (e.g., a store opening/closing). Further, SMS is useful for sending order updates or delivery confirmations, as your customers will know exactly when to expect their package and when they can go and get it. Other examples where an SMS might outperform email include your initial welcome message and general sale announcements.

Treat your SMS subscribers similarly to your VIPs; they are your brand enthusiasts who will advocate for you. Thus, include them in any special offers (e.g., early access or deals) and surveys directed at your most dedicated customers.

Email

Use an email for longer-form content, including newsletters, and any messages that you want to reach everyone in your audience, such as a product announcement.

Send any important messages you sent by SMS via email to the rest of your subscribers. The only exceptions are if you're sending an exclusive offer to SMS subscribers or are asking for feedback from this group in particular.

Billing

Your email plan is based on the number of active profiles in your account and your monthly email sends. Mobile Messaging is a separate, add-on plan. The cost of an SMS send depends on your plan’s rates, the recipients’ countries, the number of recipients, and the number of message segments.

For more information about these plans, see this article on how Klaviyo billing works.

Consent and spam

Collecting consent

Email and SMS consent are treated separately:

• Consent for email does not count as consent for SMS and vice versa.
• SMS consent must always be optional (i.e., you cannot "force" someone to subscribe to SMS when they sign up for email).

Regardless of the type of communication, it’s crucial that you have the proper permissions to message customers before contacting them. However, while you can get email consent implicitly in some cases, consent for SMS marketing must always be explicit.

How spam is treated

If someone happens to mark your emails as spam, this will impact your sending to that recipient and also hurt your inbox provider reputation.

When it comes to SMS, if someone reports you as spam to their phone carrier, you may face fines or heavy filtering.

Availability

Email is available anywhere in the world. However, you can only send SMS messages to recipients in certain countries.

If you’re both emailing and sending SMS messages within a flow, you can split the flow based on someone’s SMS consent at the beginning of the flow in order to maintain different experiences for your SMS opted-in customers and those who have not. For campaigns, you can create a segment of SMS subscribers and send to only those profiles.

Identifying your brand

When receiving an email, a recipient can look at the sender and sender email address in their inbox to know who is sending the message.

Except when using branded sender ID, which can be customized to match your brand, someone receiving an SMS message will have no idea who your brand is unless you identify yourself. You’ll need to introduce your brand in the copy of your SMS or turn on the organization prefix so customers will know who is texting them.

Conversion tracking

Klaviyo attributes purchases to messages based on your attribution model and conversion windows. By default, it uses last touch attribution, which gives credit to the last eligible message interaction before a purchase.

For new accounts, the default conversion windows for email and SMS are:

• 5 days for email opens and clicks
• 5 days for SMS clicks
• 12 hours for SMS deliveries

Your account’s settings may differ, and you can adjust these windows. For instructions, see how to change your attribution model, or learn more about conversion tracking.

Sending an email before an SMS does not automatically give the email credit for a purchase. For example, with last touch attribution, a customer might open an abandoned cart email, then click an SMS 2 days later and purchase. If the SMS click is the last eligible interaction and the purchase is within its conversion window, the SMS receives credit. Choose the order of your flow and campaign messages based on the customer experience, and check your attribution settings when comparing channel performance.

Transactional messaging

You can send both email and SMS messages to keep customers updated with their recent purchases.

All SMS messages in Klaviyo require consent, including those with transactional content. However, you can collect consent for SMS transactional messages separately from SMS marketing consent in Klaviyo.

Metrics

Both email and SMS have associated metrics that correspond to customer actions with your brand. You can use these metrics to gain business insights, trigger flows, or personalize communication with your customers.

A key difference between the channels is that Klaviyo does not track SMS opens. A Received SMS event does not confirm that someone read the message. Use SMS clicks and conversions to assess engagement and compare message performance.

Head to our articles on email metrics and SMS metrics for the corresponding metrics within your account.

Additional resources