Understanding SMS deliverability and best practices

The marketer’s guide to SMS deliverability

SMS marketing is a powerful way to deliver value directly to your subscribers’ devices. But the success of your SMS campaigns and flows hinges on one crucial factor: deliverability.

To help you maximize the impact of your marketing efforts, we’ve put together this comprehensive guide on SMS deliverability best practices.

Table of contents

Factors that impact SMS deliverability
Review your SMS deliverability
Best practices for SMS deliverability

Factors that impact SMS deliverability

Understanding the ins and outs of SMS deliverability

What is SMS deliverability? This term is used in slightly different ways from business to business, so we’ll clarify the definition before jumping into best practices.

Put simply, SMS deliverability is the percentage of time that your messages are reaching their intended subscriber’s mobile device.

To calculate your deliverability, just divide the number of successfully delivered messages by the total number of recipients and multiply by 100.

But how do you actually move the needle on this metric? To answer this, it may be helpful to first explore the factors that might impact your SMS performance.

3 critical factors that impact SMS deliverability

The type of phone number you use may affect your SMS deliverability. Some of the most common options include:

Toll-free numbers: Toll-free numbers are 10-digit numbers that begin with an 8XX prefix and are only available in the US and Canada. These numbers need to be verified, which may take around 7–10 days to process.
Dedicated short codes: Short codes are typically 5–6 digits. Brands must apply to get a short code, which takes time. But because of this process, short codes are more trusted by wireless carriers. Short codes are a good option for brands that want to avoid heavy filtering or want to send more than 30,000 messages at once.
Long codes: Long codes are country-specific. For example, if you have an Australian long code, you can’t send messages to anyone in Ireland. One of the benefits of long codes is that they allow you to receive inbound messages. Long codes have to be verified in Australia and Ireland, which may take 1–3 business days to complete.
Branded sender IDs: With branded sender IDs, you can set your brand’s name as the sender ID or number when you send one-way text messages. The same branded ID can be used across countries. There is a registration process for branded sender IDs in Australia, which takes 7–10 days to complete.

There are various levels of filtering in the ecosystem to ensure that only messages that are appropriate and desired arrive on a wireless subscriber’s handset.

For instance, carriers will typically check the content of a message for any non-compliant terms—specifically those related to sex, hate, alcohol, firearms, or tobacco (SHAFT), as well as federally illegal activity or substances, like cannabis.

A history of poor performance with your audience can also lead to filtering or suspension of your sending number. If the recipients of your messages are opting out at a high percentage, or report your messages as SPAM, this can impact your ability to send.

Once the wireless carrier approves, the message should arrive to the individual’s phone. But there are times when a text cannot be delivered.

For instance, if the recipient’s phone is off, in a location without service, out of credits, or no longer in service, your message may fail to deliver. Certain devices, such as Androids, can also filter messages into a spam folder.

As you can see, there are many factors that can affect SMS deliverability. So how do you make sure that your overall SMS performance is healthy and moving in the right direction?

Steps to review your SMS deliverability performance

To improve your overall performance, we recommend focusing on 3 metrics:

SMS delivery rate refers to the percentage of subscribers who received your message, while SMS fail rate refers to the percentage who failed to receive your message.

The goal, of course, is to keep your delivery rate high and your fail rate low. To do this, it’s important to pay attention to how often your messages are failing to send.

While you can typically expect a small number of failed messages, you want to take action if the rate is too high. Specifically, if you’re receiving error messages for more than 5–10% of your total send, you may want to consider some of the following actions:

Enabling double opt-in: Double opt-in is a feature where the SMS subscriber receives a message asking them to confirm that they want to receive communications from your brand. For example, the message might say: “Reply YES to confirm your subscription.” This is a way to make sure your subscribers actually want to hear from you to ensure a higher delivery rate.
Reviewing your message content: If your texts are frequently not getting through to your subscribers, review your message—as well as any links or landing pages—to make sure there are no references to SHAFT, CBD, etc.
Getting a short code: As we mentioned earlier, short codes go through a strict approval process and, as a result, tend to be filtered less by carriers. So if you’re dealing with carrier violation-related errors, this may be an option to consider.
Setting up an error segment: Create a segment of SMS subscribers who are unable to receive your messages so that you can exclude them from your campaigns. This will improve your deliverability and also ensures you’re not wasting your SMS credits.

SMS click rate refers to the percentage of recipients who clicked a link within your message.

According to our 2024 benchmark report, the average SMS click rate across all industries is 11.9%, while the click rate for the top-performing 10% of brands is 23.08%.

If you find that your averages are lower than these benchmarks, you may want to start using branded shortened links.

This is a way to personalize any shortened links you include in your message—making them more credible and, as a result, increasing the chances that the recipient will actually click the link.

SMS unsubscribe rate refers to the percentage of recipients who unsubscribe after receiving your message.

According to our benchmarks report, the average unsubscribe rate across all industries is 1.49%, while the unsubscribe rate for the top-performing 10% of brands is 0.37%. Again, if you find that your rates fall significantly outside of these benchmarks, it may be time to step back and assess.

Here’s what we recommend to decrease unsubscribe rates:

Personalize your messages. Typically, high unsubscribe rates are a result of sending messages that feel irrelevant or not personalized to the recipient. The easiest way to make your message feel more relevant is by using personalization variables, such as the recipient’s name or a reference to a product they purchased or abandoned.
Adjust your cadence. A high unsubscribe rate can also indicate that you’re sending too often. As a rule of thumb, 1–2 SMS campaigns per week is the sweet spot. But you might find that your subscribers require less contact, or less of a certain type of message.
Check your SMS sign-up form. To decrease unsubscribe rates, your SMS sign-up form should clearly explain and set the right expectations, including what kinds of messages subscribers will receive and how often they’ll receive them. The form should also clarify that SMS consent is optional and give subscribers the chance to opt in, or not.

Best practices for SMS deliverability

One of the challenges with any form of omnichannel marketing is figuring out how to send the right number of messages at the right times.

You want to find the right balance when texting your SMS list. Regular sends keep your brand top of mind, but sending too frequently can cause fatigue and increase opt-outs, especially if your messages aren’t personalized. The goal is to stay engaged with your audience without overwhelming them.

Even the most seasoned SMS marketers benefit from keeping these cadence best practices top of mind:

For SMS flows, keep SMS and MMS quiet hours enabled. This is generally any time before 9 a.m. or after 8 p.m. in the recipient’s time zone.
Aim to send at least 1–2 SMS campaigns per week to regularly engage subscribers.
If you use Klaviyo, take advantage of Smart Sending, which lets you control the number of emails, SMS messages, or push notifications someone can receive within a set period of time.

When setting up SMS campaigns, use segmentation to your advantage. Here are two SMS segments we recommend focusing on to improve deliverability:

Error segment: As we mentioned earlier, an error segment excludes SMS subscribers who are unable to receive your messages. By excluding this demographic, you can increase your deliverability and avoid wasting SMS credits on people who aren’t likely to receive your messages.
Unengaged segment: This segment definition may vary from business to business, as what “unengaged” means strongly depends on how often a business sends SMS and their typical buying cycle. But for someone sending weekly, a typical unengaged segment may include those who haven’t clicked an SMS and didn’t visit your website in the last couple of months. We recommend sending to your unengaged segment at least once a month.

By strategically using segments in your SMS campaigns, you can improve deliverability while ensuring your subscribers are only receiving the messages that they actually want to see from your brand.

Choosing the right marketing platform can have a significant impact on your SMS deliverability. Plus, the best platforms serve multiple functions.

First, the top SMS platforms bake compliance and deliverability features right into their technology. They also surface critical information that removes the guesswork for your team—saving you valuable time and resources—so you can understand exactly what changes you may need to make to future messages.

Klaviyo, for instance, shares the deliverability rate for each text message you send, as well as insights into why individual messages weren’t delivered.

We also recommend choosing a platform that bundles SMS and email under one roof. This empowers you to see how your customers are interacting with both of these channels, all in one place.

It also helps you make smarter marketing decisions, such as sending messages to your customers through the channels they prefer or creating a more seamless omnichannel experience.

Want to improve SMS deliverability with Klaviyo?

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The marketer’s guide to SMS deliverability

Understanding the ins and outs of SMS deliverability

3 critical factors that impact SMS deliverability

1. Your phone number

2. The content and quality of your messaging

3. The recipient’s mobile device

Steps to review your SMS deliverability performance

1. Delivery rate/fail rate

2. Click rate

3. Unsubscribe rate

Best practices for SMS deliverability

Strike the right balance in timing and frequency

Focus on segmentation

Invest in the right platform

Want to improve SMS deliverability with Klaviyo?