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 maximise the impact of your marketing efforts, we've put together this guide on SMS deliverability best practices.
Understanding the ins and outs of SMS deliverability
SMS deliverability is the percentage of time your messages successfully reach your intended subscriber's mobile device. You can calculate it by dividing the number of messages successfully delivered by the total number of recipients, then multiplying by 100.
A number of factors affect deliverability, from the type of number you send from to the content of your messages and your subscribers' devices.
3 critical factors that impact SMS deliverability
Your phone number
Toll-free numbers are 10-digit numbers with an 8XX prefix, available in the US and Canada, and typically take 7 to 10 days to verify. Dedicated short codes are 5 to 6 digit numbers that require an application but benefit from better carrier trust, making them a good option once you're sending to more than 30,000 recipients per send. Long codes are country-specific numbers that allow inbound messages and typically take 1 to 3 days to verify in markets like Australia and Ireland. Branded sender IDs display your brand name as the sender and, in Australia, take 7 to 10 days to register.
The content and quality of your messaging
Carriers filter messages containing SHAFT terms (sex, hate, alcohol, firearms, and tobacco) as well as references to federally illegal substances like cannabis. A poor engagement history, such as high opt-out or spam report rates, can also cause your messages to be filtered, or your sending capability suspended.
The recipient's mobile device
Sometimes deliverability issues have nothing to do with your messaging: a recipient's phone might be off, out of service, out of credit, or no longer active, and Android devices in particular can filter messages into a spam folder.
Steps to review your SMS deliverability performance
Delivery rate and fail rate
Your delivery rate is the percentage of messages that successfully reach a device, while your fail rate is the inverse. If you're failing to deliver more than 5 to 10% of your sends, consider enabling double opt-in, reviewing your message content for SHAFT or CBD-related terms, moving to a short code, or setting up an error segment to exclude contacts who consistently don't receive your messages.
Click rate
Your click rate shows how many recipients are engaging with the links in your messages. Compare your own rates against Klaviyo's current SMS marketing benchmarks by industry to see how you stack up, and check out our guide to branded shortened links for ways to improve clickthroughs.
Unsubscribe rate
A high unsubscribe rate is often a sign that your messaging needs adjusting. Personalise your messages, review your sending cadence (1 to 2 SMS campaigns a week tends to be the sweet spot for most brands), and make sure your SMS sign-up form sets clear expectations about what subscribers will receive.
Best practices for SMS deliverability
Strike the right balance in timing and frequency
As part of a broader omnichannel marketing strategy, avoid sending outside of quiet hours (before 9am or after 8pm in the recipient's local time zone), and aim for 1 to 2 campaigns a week. Klaviyo's Smart Sending feature can help you cap frequency automatically across channels.
Focus on segmentation
Build an error segment to exclude contacts who aren't receiving your messages, and an unengaged segment for subscribers who haven't clicked a message or visited your site in the last couple of months — sending to this group at least monthly can help you win back their attention.
Invest in the right platform
The best SMS platforms build compliance and deliverability into the sending experience, rather than leaving you to work it out alone. Klaviyo shows you a per-message deliverability rate alongside insights into why any given message failed, and because SMS and email sit on the same platform, you get one view of engagement across both channels.
Klaviyo customers can also use the SMS deliverability hub, a centralised reporting view for diagnosing SMS deliverability health across all your sends, so you don't have to calculate these metrics by hand.
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