February 20, 2023
Reading Time: 4 minutes
Though often overlooked, SMS deliverability is one of the most important ingredients in a successful SMS marketing program. After all, subscribers can’t convert on messages they never receive.
Your deliverability rate measures the percentage of messages that actually reach the intended recipients. People often confuse deliverability with throughput, which is a separate (but almost as important) factor. Throughput is about how fast the message reaches its recipient.
While SMS open rates remain high as adoption of this channel increases, many marketers are getting hit with declining deliverability rates and encountering more issues with throughput. And that can take a big bite out of SMS marketing ROI.
5 Factors that Inhibit SMS Deliverability
So, what can you do to make sure your text messages get to your subscribers’ phones? First, you need to understand what’s affecting your deliverability rate. It basically boils down to the carriers, your content, your data, and your SMS platform.
1. Poor list quality
One surefire way to encounter deliverability issues: sending messages to invalid numbers. This is the text equivalent of a bounced email to an invalid email address.
Invalid numbers can creep into your database in two ways:
The subscriber provided a fake number or a landline number in the first place.
The phone number is disconnected.
2. Subscriber phone issues
Device issues are another common cause of SMS failures. This happens for a couple of different reasons:
If a phone is turned off or in a roaming area when your message sends, the carrier may not be able to deliver it.
Believe it or not, some cell phones simply aren’t capable of receiving SMS or MMS messages.
3. Carrier outages
Carriers are delivering a lot of messages and can only effectively process a certain volume of them at any given time. Many SMS platforms—including Postscript—have queuing mechanisms in place to ensure that all messages are sent (even if those messages are delayed due to a spike in sending volume). These delays reduce your message throughput—a.k.a. sending speed.
Some SMS providers don’t have a process in place to prevent message failures during high-volume periods. As a result, delayed messages simply never reach their recipients. (So, it’s important to evaluate the capabilities of any platform you’re considering.)
Outside of bandwidth constraints, carriers occasionally experience outages. Often characterized as “downstream impact,” these outages sometimes result in delayed or failed messages. The impact of a carrier outage varies depending on the type and nature of the outage.
4. Carrier filtering
Network carriers—including Verizon, AT&T, and T-Mobile—are the entities actually responsible for sending messages to subscribers’ phones. They’re also responsible for enforcing the rules and regulations around SMS marketing and filtering those messages for spam, fraud, and restricted content.
While their goal is to protect subscribers from unwanted messages, they sometimes unknowingly filter out fully-compliant messages that should by all rights reach your subscribers.
5. Your SMS platform
Carriers don’t just look at your brand’s messages and sender reputation. They also look at the reputation of the SMS platform you’re using. This means your platform’s other customers could wind up dragging you down.
Some carriers actually implement specific compliance regulations for any messages sent through platforms that have a high volume of spam reports. If you’ve experienced a substantial drop in your deliverability rate—and you know that neither your content nor your data are the issue—then you may want to evaluate the platform you’re using.
Tips to Improve SMS Deliverability
While you can’t solve all these problems on your own (e.g., you can’t force your subscribers to keep their phones on), there’s a lot you can do to ensure your text messages get where they need to be.
Improving deliverability basically boils down to two things: following all the best practices within your control and choosing tools that will make all the other parts easier.
Specifically, we recommend that you:
Require double opt-ins: When someone new subscribes to your text messages, immediately send them a second opt-in message asking them to confirm that they want to join your list. If they don’t reply “Yes” to the second message, don’t add them to your subscriber list. This is a great way to filter out bad phone numbers.
Make it easy to opt out: It’s a good practice to remind people about how they can unsubscribe from your updates. We recommend sending opt-out reminders to subscribers one to two times per month. (Note that the CTIA requires this reminder at least once per month.)
Send a contact card campaign. We recommend periodically sending a campaign with your contact card attached and asking subscribers to save you in their contacts. It’s also a good idea to include your contact card as part of your welcome series. You can learn more about the how and why of contact cards here.
Get personal: The more personalized your messages, the more engagement they will drive. Automations, filters, and segments can all help you create highly personalized campaigns that your customers will love.
Engage in conversations: Talk with your customers, not just at them. Brands that converse with their customers via text not only have higher deliverability rates, but also generate significantly more revenue from SMS marketing than merchants who only use this channel to send one-way messages. (Check out some great conversational campaign ideas here.)
Be mindful of junk reporting. It's easy for text messages to blend together and for people to forget that they subscribed to your updates. That's why we suggest encouraging subscribers to save you as a contact and identifying your brand in every message you send. This will help ensure they don’t accidentally mark your message as junk.
Use shortcodes or TFNs: The number that your text messages come from affects your throughput rate. You’ll want to work with your SMS provider to determine the best phone number for your brand's specific needs (e.g., your mix of SMS versus MMS) and your typical sending volume. Postscript recommends that ecommerce brands use either a dedicated shortcode or a dedicated toll free number (TFN), as these are the best options for brands with more subscribers and higher sending volumes than, say, local businesses or brick-and-mortar stores.
Think SMS over MMS: Consider sending SMS campaigns during peak times instead of MMS campaigns. They encounter far fewer obstacles. If you do send an MMS campaign during high-traffic times, be sure to enable an SMS fallback.
Choose the right SMS platform: Not all SMS platforms are created equal. You want a platform that automates the double opt-in experience, has strong compliance guardrails in place, and values carrier relationships. That’s where Postscript comes in.
Using Technology to Increase SMS Deliverability
The right tools will help you maximize deliverability rates so you can unlock the full revenue potential of your text marketing efforts.
Your SMS platform should:
Automate double opt-in compliance
Help identify data hygiene issues
Be obsessed with carrier relations
Offer a solid and scalable infrastructure that can meet growing market demands
Postscript’s deep partnership with Twilio delivers unrivaled deliverability and throughput. With our most recent expansion of this relationship, brands on our platform receive 3 times more bandwidth and 90% less latency. This integration powers real-time visibility into carrier queues so we can proactively identify and address delays before they reach any of our merchants.
This integration is so effective that none of the 9,000 Shopify or Shopify Plus stores using our platform experienced any deliverability incidents during the 2022 Black Friday and Cyber Monday shopping season.
Want to learn more about all the ways Postscript can maximize your SMS deliverability and throughput? Get in touch with our team here.
Principal Market Intelligence Manager
Mindy Regnell is the Principal Market Intelligence Manager at Postscript. Over the last 15 years in ecommerce, she has run an online store, studied over 30 different ecommerce platforms, and tracked the latest trends. When she isn’t geeking out on SMS or ecommerce, Mindy can almost always be found quilting up a storm.