Guide to Message Deliverability and Throughput

At Postscript, the successful delivery of your messages is a top priority. We wanted to share a transparent look into the deliverability process. In this article, we:

  • Define deliverability and throughput rates - these two concepts together paint a better picture about how your SMS program is operating.
  • Take you through the deliverability process from start to finish and discuss which parts your shop, Postscript, and the carriers control.
  • Discuss common causes of deliverability issues and recommend some best practices.

To navigate quickly to specific sections of this article, you can select any of the hyperlinked sections listed on the In this article card.

Understanding Throughput and Deliverability

SMS Delivery measures outgoing SMS and MMS messages that are received at their intended destination. Deliverability measures the difference between total delivered messages and total outgoing messages.

Throughput Rate is the rate at which messages can be sent, or move through messaging "roadways", within a given timeframe. In other words, throughput rate measures how long it takes for a subscriber to receive your message. Throughput rate can vary based on how busy the messaging roadways are and what kind of phone number a shop is using to send messages (e.g. shortcodes vs. toll-free numbers). The type of phone number a shop uses to send messages determines the size of the messaging "roadways". Postscript sends your messages to the carriers quickly, however the throughput rate is controlled by carriers and limited by overall system constraints (including several other users, including non-marketing use cases).

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Sending messaging from a shortcode is like traveling in the express lane on a highway. It’s built for high volume and top speed (and has a more involved process to get things up and running as well as a higher cost for the phone number) so these roads are accustomed to high throughput whereas sending SMS messages from a TFN is like traveling on a multi-lane highway. However, sending MMS from a TFN is like traveling on a congested 2-lane highway. When you send during peak sending times, the roadways are smaller and heavily trafficked. 

Postscript’s partnership with Twilio allows merchants three times the bandwidth we received for BFCM 2021. You can think of this partnership as opening up an HOV lane on a two-lane highway for SMS messages. That means better throughput for Postscript merchants on both toll-free numbers (TFNs) and shortcakes. While this partnership improves throughput rate, keep in mind that carriers have a finite infrastructure that is limited by overall system constraints (including several other users with both marketing and non-marketing use cases).

If you consider the holiday season, as many businesses prepare for their busiest time of year, the number of marketing messages increases. This additional volume can turn what is normally a simple drive down a big highway into a highly trafficked drive as more cars get on the same highway. As a result, it takes longer to reach your destination.

Postscript and Mobile Carriers

When you send a message to your subscribers, Postscript works with network carriers to deliver those messages. In this section, we break down which entity has the most impact on each part of the delivery process.

Your Shop Postscript Network Carriers

While Postscript and network carriers play an important role in the message delivery process, the below are actions your shop can take to ensure you are viewed by the carriers as a trustworthy source.

  • Collect explicit opt-in consent from every subscriber using compliant list growth methods.
  • Create messages (including GIFs/images, copy, and promotional offers) to send to your subscribers.
  • Choose a phone number type (e.g., short code, toll-free, etc.) that best supports the volume of messages you wish to send.
  • Keep messages concise, engaging, and free of restricted content.
  • Provide opt-out opportunities (we recommend at least once a month).

What Impacts Message Deliverability

Several factors can impact deliverability, or the percentage of messages that actually reach the intended recipients.

Poor List Quality Message Filtering Message Volume Phone Issues

Maintaining the hygiene of your SMS contact list is not only essential for understanding how your SMS program is performing, but it also gives your brand the best chance for optimal deliverability. 

Having a "clean" list yields clearer analytics--because it's not taking into account unengaged or invalid numbers, and it's cost effective.

What You Can Do

  • Send Opt-Out Reminders. Subscribers may become less engaged over time. If you continue to text them too frequently, it can leave a bad impression. Give your subscribers the option to opt-out of your SMS program in order to preserve your brand reputation.
  • Send a win-back campaign to an unengaged segment in order to give subscribers the opportunity to opt out of receiving future SMS messages or to re-engage with your brand by indicating what kind of SMS messages they want to receive. Learn how here.
  • Send hyper-targeted messages more often. Send personalized messages to various pockets of your most engaged subscriber base rather than sending blanketed or mass campaigns.
  • Implement confirmed opt-in. Postscript takes a product-led approach to compliance meaning features like confirmed opt-in (sometimes called double opt-in) are built into our app. Confirmed opt-in requires a subscriber to confirm their intent to subscribe to your shop. By utilizing confirmed opt-in, you can be sure that your list is devoid of inactive or inaccurate numbers.

Additional Resources

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