Getting Started with Klaviyo SMS and MMS

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Get started with SMS marketing; learn how this channel can take your marketing strategy to the next level, general best practices, and how to set SMS up in Klaviyo. 

SMS marketing is a broad term and covers two types of text messages: SMS and MMS. SMS stands for "short messaging service," while MMS stands for "multimedia messaging service." The key difference between SMS and MMS is that MMS enables you to attach images and GIFs to your text messages. 

This article is for those who are already using Klaviyo for email but are new to SMS marketing. If you are not already using Klaviyo for email, read Getting Started with Klaviyo

Why Use SMS?

Around the world, more and more people use their phones and tablets to discover and research products, purchase, leave reviews, and more.

SMS marketing can help you reach these customers directly. What’s more, SMS provides several benefits over other channels. SMS messaging is:

  • Instant — Around 98% SMS messages are opened, and most are read within the first three minutes; this makes it particularly good for important or time-sensitive messages
  • Highly engaging — SMS typically outperforms every other marketing channel for engagement 
  • Direct — SMS go straight to a recipient’s phone and actively ping it, alerting them as soon as the message is delivered
  • Personal — SMS can be personalized for each individual, making your marketing messages feel like a one-on-one conversation

But do people actually want to get SMS marketing messages? Most say “yes.” In 2019, 54% of consumers said they wanted to receive text messages with promotions. Further, since COVID-19 started, even more people are using their mobile devices to shop online rather than in stores. 

SMS Use Cases

Now the question is: what can you do with SMS marketing? Below are common use cases: 

  • Discounts, coupons, and deals
  • Exclusive offers
  • Early access to products or promotions
  • Appointment reminders 
  • Flash sales
  • Alerts for releases 
  • Transactional messages
  • Surveys, polls, and feedback
  • Customer support 

SMS Best Practices

New to SMS? Tune into a 30-minute live session on SMS setup, deliverability, and more.

Before you start with SMS marketing, it’s best to learn the dos and don’ts of this channel. 



Provide value in every message

Text anyone who has not opted into SMS

Keep SMS messages short and concise 

Use abbreviations or text-speak unless you know your audience will understand and appreciate them

Send only between 9 am and 8 pm in the recipient’s local timezone; use SMS quiet hours for flows

Send too frequently (i.e., more than six times per month)

Let recipients know who the messages are coming from (e.g., mention your brand name)

Send an SMS for everything — be strategic and intentional

Include opt-out instructions in your messages

Include any spam-like content or phrases related to sex, hate, alcohol, firearms, or tobacco (SHAFT) or CBD

Include a link and use the Klaviyo link shortener

Neglect other channels, such as email, as it’s important to use SMS and email together for the best results

*Use double opt-in; some individual carriers require this for SMS abandoned cart flows, but it is also recommended in all cases


Use a verified toll-free number or short code when sending SMS or MMS


*Double opt-in is skipped for subscribers in the UK and Australia. This is because alphanumeric sending IDs, which are used for Klaviyo SMS in these countries, don’t allow recipients to text back. 

Checklist for Klaviyo SMS

It’s now time to talk about how to use SMS in Klaviyo. Currently, you can collect SMS consent and send text messages in the United States, Canada, United Kingdom, and Australia. Not in one of these countries but want to use SMS? Stay tuned! We're working hard to bring Klaviyo SMS to other areas. 

We recommend following the steps below in order to achieve the simplest setup process and to quickly get up and running. 

  1. Enable Klaviyo SMS (2 minutes)
  2. Choose your SMS plan (3 minutes)
  3. Update your terms of service and privacy policy (12 minutes)
  4. Create an SMS subscribers segment (2 minutes)
  5. Improve your welcome series (9 minutes)
  6. Collect SMS subscribers (10 minutes)
    • Update old signup form
    • Collect SMS consent at checkout (if applicable)
  7. Add SMS to your abandoned cart flow (5 minutes)
  8. Send an SMS campaign (4 minutes)

Enabling Klaviyo SMS

Before doing anything else, you must enable SMS in Klaviyo. 

After you enable SMS, you will automatically receive a toll-free number that you can use to send to the US and Canada. 

How to Enable SMS

  1. Click on the name of your organization in the upper right-hand corner 
  2. Select Account from the dropdown
  3. Navigate to Settings > SMS 
  4. Click Set up SMS for free
  5. Click Continue

Set Up Your Alphanumeric Sender ID

If you plan to send in the UK or Australia, edit your alphanumeric sender ID to indicate your brand. Setting this up is key, as you will not be able to collect SMS consent from people in these countries until you have an active alphanumeric sender ID.

Alphanumeric sender IDs must:

  • Be under 11 characters 
  • Contain at least one letter
  • Not have any special characters (e.g., ~, &, etc.)

How to Customize Your Alphanumeric Sender ID

  1. Navigate to Account > Settings > SMS
  2. Click either: 
    • Confirm Sender ID
    • The dropdown menu on the right-hand side of the alphanumeric number and then choose Edit
  3. Add your alphanumeric sender ID in the modal
  4. Click Save 

Choose Your SMS Plan

We recommend starting with the free plan to test how well SMS works for your audience. 

As you scale, ask yourself the following questions when choosing an SMS plan: 

  • Where are your SMS recipients located?
  • How many text campaigns do you plan to send per month? Are any of them MMS campaigns?
  • How many text messages are in your flows? Are the messages SMS or MMS? 
  • How many SMS subscribers do you have?
  • Are you planning any lead generation events soon?

MMS messages count as more sends than SMS messages. Further, this number varies by country, so consider this when picking a plan. The phone number and country comparison chart below tells you how many sends an SMS or MMS counts as in each country. 

How to Upgrade Your SMS Plan

  1. Navigate to Account 
  2. Click Billing > SMS Plans
  3. Review the number of profiles and messages available for a potential plan
  4. Click Change to switch to that plan

Your Sending Numbers

Every plan includes an alphanumeric number and either a toll-free number (for lower-tiered plans) or a short code (for higher-tiered plans), ensuring you can send to every country where Klaviyo SMS is available. 

Phone Number and Country Comparison Chart



UK and Australia

Sending number types

- Toll-free number

- Short code

- Vanity short code

- Toll-free number

- Short code

- Vanity short code

- Alphanumeric

Number of sends per message type

1 send for SMS

3 send for MMS

1 for SMS

3 for MMS

3 for SMS

Opt-in and opt-out keywords






Toll-free = available

Short codes = unavailable


SMS conversations (two-way messaging)




Update Your Terms of Service and Privacy Policy

This information is not legal advice. Consult with your legal counsel to make sure that you comply with applicable laws in connection with your marketing activities. 

General business best practice is to let customers know what you’ll do with their data via a terms of service and privacy policy. 

See the following articles for further guidance

Create an SMS Subscribers Segment

Segments update automatically: profiles will enter or leave the segment when they meet or fail to meet the segment’s conditions. This is different from lists, which are static and only add or remove profiles when they subscribe or fully unsubscribe. Lists also don’t remove profiles when they unsubscribe from one channel but are consented for another channel; for example, a list will still include someone after they opt out of SMS if they are still consented to email. Thus, segments are a more accurate way to look at who is subscribed to SMS. 

It can also be difficult to know how many SMS subscribers you have, as they may be spread throughout different lists or you may have a list that shows both your email and SMS subscribers together. An SMS subscriber segment will show you everyone who is opted into SMS so that you can see all of your subscribers at once. 

How to Create an SMS Subscribers Segment

  1. Go to Lists & Segments > Create List/Segment > Segment 
  2. Name your segment 
  3. Add the condition:
    If someone is or is not consented to receive SMS 
  4. Keep the condition as:
    Person is consented to receive SMS
  5. Click Save 

Improve Your Welcome Series

Next, set up a flow to welcome your SMS subscribers to your brand community. This will be the first time someone receives an SMS from you, so make sure you create a good impression. You’ll also want to make sure your SMS and email welcome series don’t compete with each other. 

Create an SMS-Only Welcome Flow 

Because most SMS subscribers don’t want to receive messages too frequently, we suggest including only one message in your welcome series. 

In Klaviyo, it’s important to create a new SMS flow for your welcome series, rather than including an SMS in your email welcome series. This separates the two channels and ensures that anyone who went through the email flow can still receive the SMS welcome message.

How to Create an SMS Welcome Series

  1. Navigate to Flows > Create Flow > Create from Scratch
  2. Choose Metric as the flow type
  3. Select Consented to receive SMS from the dropdown for the flow trigger
  4. Add a flow filter for Has not been in this flow at any time
  5. Click Save > Done
  6. Drag in an SMS directly after the trigger
  7. Create the content for the SMS or MMS
  8. Click Save Content
  9. Change the status to Live
  10. Click Save & Exit 
Tips: Message Content

For the message itself, there are few key parts you want to include: 

  • *Your brand/organization name 
  • A line thanking subscribers for signing up
    • Welcome to the club!
    • Thanks for joining [your brand] texts!
  • Any incentive you offered for signing up
    • Here’s your 15%: [insert coupon]
    • Take 10% off any time with [insert coupon]
    • See exclusive products here [add link]
  • A link to your site using the Klaviyo link shortener
  • *Opt-out instructions
    • Text END to opt out
    • Unsubscribe via this link: [add link]
  • *Contact information [for certain jurisdictions] 

Any parts marked by the asterisk (*) are added by default. While you can toggle off these options, this is not recommended for compliance reasons. If you do remove these, insert your version after consulting with your legal counsel. 

Tips: Message Count

When creating messages, keep in mind how long the message is. While MMS messages can be up to 1,600 characters, SMS messages are limited to 160 characters. Having an emoji or special character also decreases this limit to only 70 characters for SMS. 

The message type and number is shown on the left-hand side so that you can know how this message will affect your plan. Further, consider who will receive this message. For the example below, this message equals two SMS. For recipients in the US, this will count as two sends; however, it will count as six sends for anyone in the UK. 

Sample text that equals two SMS messages

Note that even if a message counts as multiple messages, due to the way text messages are displayed, it will show as a single message both in the Klaviyo preview and on the recipient’s phone. 

Update Your Email Welcome Series

Think about the experience you want a new subscriber to have when they first sign up, particularly if they sign up for both SMS and email. 

We recommend sending the SMS first. Wait at least 10 minutes before sending out the email so that the messages don’t compete with each other. 

How to Update Your Email Welcome Series

  1. Add a conditional split with the condition:
    Is not consented to SMS
  2. Drag in a time delay — that’s, at minimum, 10 minutes — onto the No path; here, the time delay is set for four hours
  3. Clone the first email in the flow
  4. Drag the cloned email to be after the time delay in the No path
  5. Review and edit the email 
  6. Click Save Content > Done
  7. Change the message status to Live
  8. Rejoin the Yes and No paths

Collect SMS Subscribers

Now that you have your welcome series set up and ready to send, it’s time to gather SMS subscribers. This is the keystone of your SMS strategy; without subscribers, you’ll have no one to send to. 

There are two basic steps to collect SMS subscribers: 

  • Update your existing signup form(s)
  • Collect SMS consent at checkout

When gathering SMS consent, there are several important aspects to keep in mind:

  • Express consent is required for all SMS messages (including transactional), meaning subscribers must:
    • Tell you directly that they want to receive marketing messages via text from your brand 
    • Know that they are opting into SMS marketing
  • Consent for email (or any other channel) does not count as consent for SMS
  • It’s important to tell customers how and when you’ll text them and to include links to your terms of service and privacy policy

Update Your Existing Signup Forms

Change any live forms you use to collect email subscribers to also gather SMS subscribers. The best way to do this is by making your one-step forms into multi-step forms. The first page of the form will stay exactly the same; you’ll simply add another page for SMS consent. This way, you can collect SMS consent from new subscribers without slowing down your email list growth.

How to Change Existing Forms to Collect SMS Consent 

  1. Navigate to the form you want to update
  2. Click Edit Form in the upper right
  3. Click Add Step 
  4. Choose SMS Opt-in
  5. Select your list (we strongly recommend using a list where double opt-in is enabled)
  6. Click Add Step
  7. Edit the disclosure text to include links to your terms of service and privacy policy
  8. Click Publish to update the form 

Collect SMS Consent at Checkout (if Available)

Getting people to sign up at checkout is one of the best ways to grow your SMS subscriber list. It’s a way to ask for SMS consent from all customers (and potential customers) without intruding on their shopping experience.

SMS consent at checkout is only available for certain integrations, and each treats it a little differently. Click on the name of your integration from the list below to see how to set up SMS consent at checkout: 

Update Your Abandoned Cart Flow to Include SMS

SMS is a great tool for sending text reminders about abandoned items. Note that you can only send these reminders to opted-in subscribers. 

Only use one SMS message in any abandoned cart flow (or browse abandonment flow). Further, the SMS should be sent within 24 hours of a subscriber abandoning their cart. Carriers may see you as a suspicious sender and filter your messages if they detect that you send too many SMS messages in this flow, or if you send the messages too late. 

How to Add SMS to Your Abandoned Cart Flow

  1. Navigate to your abandoned cart flow
  2. Add a conditional split after the first time delay with the condition:
    Is not consented to SMS
  3. Drag an SMS action after the split
  4. Create the content for the SMS or MMS
  5. Click Save Content
  6. Change the message status to Live
  7. Rejoin the No and Yes paths directly after the message
  8. Click Save & Exit 

Similar to your SMS welcome message, the following are all important to include in your SMS abandoned cart message:

  • *Your brand/organization name 
  • A line telling subscribers they left something behind
    • Uh-oh, you left something behind
  • Indicate a product the customer left behind via a dynamic event variable (e.g., the product name) or a dynamic image 
    • Note: The dynamic image will not show when the message is sent from an alphanumerice sender ID (e.g., in the UK and Australia)
  • Any incentive you want to offer for someone to purchase
    • Buy now and get 15% off: [insert coupon]
    • Get free shipping when you purchase with code [insert coupon]
  • A link to your site (or cart, if available) using the Klaviyo link shortener
  • *Opt-out instructions
    • Text END to opt out
    • Unsubscribe via this link: [add link]
  • *Contact information [for Canadian recipients] 

Any parts marked by the asterisk (*) are added by default. While you can toggle off these options, this is not recommended for compliance reasons. If you do remove these, insert your version after consulting with your legal counsel.

Send an SMS Campaign

The final step to getting started with SMS is sending a campaign to your subscribers. For your first SMS campaign, it’s important to provide unique value to subscribers. Do not send an SMS with information that someone received earlier via email or saw on your social media pages. This information should be either sent only to SMS subscribers or should be sent to them first. 

If you’re not sure where to start, below are a few ideas you can use as a launching off point. 

  • Flash/limited-time sale notification
  • Alert for a new release
  • Early access to a sale, release, etc.
  • Message with exclusive and important information

How to Create an SMS Campaign

  1. Navigate to the Campaigns tab
  2. Click Create Campaign
  3. Select SMS in the modal
  4. Click Create Campaign in the modal
  5. Name the campaign
  6. Choose which list(s) or segment(s) to send to
  7. Click Save & Continue to Content
  8. Write out your text in the Message Content box
  9. *Add in any emojis, images, or GIFs 
  10. Click Save & Continue to Review
  11. Review the settings for the campaign, confirming that the message will send to the right audience and tracking is enabled
  12. Click Schedule or Send
  13. Choose Schedule to send the campaign at a later date, or Send Now to send the campaign immediately
  • Emojis will shorten the character count from 160 for an SMS to 80. 
  • Images and GIFs turn the SMS into MMS, which increases the character count to 1,600; however MMS: 
    • Count as more sends
    • Are not supported for alphanumeric sender IDs, so the image and GIF won't show for all recipients 

Keep the best practices in mind when creating an SMS or MMS campaign: 

  • Reference your brand name
  • Make the message as short as possible 
  • Only send between 9 am and 8 pm in the recipient’s local timezone
  • Include a link and use the Klaviyo link shortener
  • Wait to send until you have a verified toll-free number or short code
  • Keep your audience in mind, both in terms of your language, whether you have any image or GIFs, and how it will count toward your SMS plan

Next Steps

Congratulations, you’ve learned the basics of Klaviyo SMS. Below, we’ve included resources that can help you as you grow your SMS marketing efforts. 

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