SMS deliverability guide

SMS marketing is a fairly new and growing channel for marketers to communicate with their database. While it is often thought of in relation to email as a potential resource, the limitations around SMS marketing are very strict in comparison and require awareness in order to be able to maintain continued use of it.

In this guide you will find best practices, compliance requirements, and advice for troubleshooting issues with SMS delivery.

SMS best practices

This section outlines a number of best practices for SMS marketing.

Goal metrics

While industry, audience, and content-type can all affect engagement expectations, here is a general guide of goal engagement rates for a healthy SMS campaign:

• Click rate: > 7.5%
• Bounce rate: < 1.5%
• Unsubscribe rate: < 1%

If your SMS campaigns do not meet these thresholds as they should, then it is an indicator that your SMS strategy, opt-in practices, or technical configuration requires further investigation to identify opportunities for improvement (tips for which are provided in the following sections).

Compliance requirements

Ortto’s SMS feature is supported by Twilio. The following compliance requirements are in alignment with Twilio’s Messaging Policy:

• Consent: All recipients must have explicitly opted into receiving SMS communications from your organization.
• Sender identification: You must clearly identify yourself as a sender in every message received by your recipients.
• Ability to revoke consent:
  • All initial contact via SMS should include clear instructions for the recipient on how to opt out (Reply “STOP”, etc).
  • While providing an opt-out link or reply to opt-out option with each message is not always required by certain regions, it is a requirement within Ortto when you compose an SMS message.
• Content restrictions:
  • For US/Canada traffic, none of these industries/content-types are allowed.
  • Check this link for further content that is not allowed.
• Follow all regional-specific requirements, including delivery time and content restrictions, for messages:
  • Depending on your country and the country of your recipients, you may have further requirements to fulfill to assure better SMS deliverability.
  • All messages should comply with the rules applicable to the country in which the message recipient lives. Twilio has country-specific requirements for select countries, which you should review prior to sending a message to recipients in or from those countries.
• Do not enact sending practices that attempt to evade and sneak past abuse-monitoring/reporting measures.

Best practice guidelines

Everything from your technical configurations to message strategies affect your SMS campaign performance and deliverability.

Here are some best practices to help maintain reliable delivery experiences and strong engagement metrics:

• Choose the optimal sender ID that is recognizable by your audience. Learn more about Ortto’s sender ID feature.
• Utilize confirmed opt-in. Learn more about opt-in consent.
• Keep the content focused, organic, and as un-spam-like as possible:
  • Avoid using more than 320 characters in messages or risk experiencing deliverability issues with carriers.
  • Avoid using public link-shorteners like bit.ly. Try to find a way to use your own, personalized domain for link shortening.
  • Avoid over-using emojis.
  • Avoid unnecessary capitalization and punctuation.
  • Keep the tone human and engaging, rather than sounding like a flyer or radio commercial.
  • Use SMS to elevate only personally relevant messages to recipients and utilize other channels for one-to-many general outreaches.
• Some countries do not allow two-way messaging, especially when sending from outside the recipient country.

SMS should be used more in a transactional capacity, as a follow-through operation in response to a customer’s actions/activities (such as to confirm an order or delivery), and it should be used in a way that is expected and appreciated by the recipient.

Some surveys have found that SMS sees a 90% open rate on average. If your click rate is below healthy industry benchmarks, it is time to re-evaluate your strategies with the above best practices.

Delivery issue investigation

Multiple elements are involved to deliver your SMS messages to your recipients and, just like with email, delivery issues can be related to a problem from any one of these elements.

In general, these are the categories of delivery-affecting elements in the SMS process:

• Sender practices: From the current message being created to messages sent previously, a sender’s send-practices affect their ongoing deliverability.
• Message-build platform (Ortto, in this case): Errors can occur when the message-build platform must package and hand off the SMS traffic to the message-send platform.
• Message-send platform (Twilio, in this case): The message-send platform must be able to accept the traffic from the message-build platform, verify everything is in order for delivery, and be able to properly connect and communicate with each carrier for each recipient.
• Recipient carrier (and related systems): The recipient carrier must be able to accept the traffic from the message-send platform, verify everything is in order for delivery, check reputation and block settings, and be able to properly connect and communicate with each recipient’s device.
• Recipient device: The recipient’s device must be able to connect to the carrier and receive the message.

There are a lot of moving pieces to messaging, but it is very similar to email in this way. And just like with email, there are various system configurations and alerts set up to attempt to self-resolve or alert of issues needing to be addressed.

Spam filtering

Outside of technical issues, SMS delivery issues can also occur due to perceived spam-like activities.

While a few carriers/applications have begun experimenting with a spam folder of sorts for SMS messages, most carriers don’t have this sort of nuanced capability as of yet.

This means that, in general, when a carrier system receives a message of questionable quality its filtering decision will simply be to not deliver to the recipient at all.

Thankfully, error codes around such delivery failures help guide investigations on how to resolve issues as they arise.

Bounce reasons

The following bounce reasons can appear against undelivered SMS recipients in the Reason field under the Bounced SMS activity:

• Unknown destination handset:
  • Meaning: The destination carrier is reporting the to (intended recipient’s) number is unknown, or no longer in service
  • Resolution: Communicate with the subscriber via other channels to verify number is accurate and active.
• Unreachable destination handset:
  • Meaning: The destination carrier is reporting the to number is unreachable — the device is likely powered down, out of the service area, or may not accept your messages.
  • Resolution: Wait and see if the issue continues with the next attempt. If it does, communicate with the subscriber via other channels to verify number is accurate and active.
• Carrier violation:
  • Meaning: The destination carrier is filtering out your messages for delivery.
  • Resolution: Check your content in comparison to carrier regulations based on recipient region:
    • US & Canada
    • International guidelines by country.
• Unknown error:
  • Meaning: The destination carrier has returned a generic error message.
  • Resolution: Check your content in comparison to carrier regulations based on recipient region and look for a trend in carrier-related recipients with the issue. If issue is ongoing, reach out to Ortto’s Support team (click Support within the Ortto app to submit a ticket or email help@ortto.com) for further assistance in investigating.
• Message blocked:
  • Meaning: Your message has been blocked from reaching the destination.
  • Resolution: Communicate with subscriber via other channels to verify number is accurate and active. Check your content in comparison to carrier regulations based on recipient region and look for a trend in carrier-related recipients with the issue. If issue is ongoing, reach out to Ortto’s Support team for further assistance in investigating.
• Landline or unreachable carrier:
  • Meaning: The destination is a landline phone, or the destination carrier can’t be reached.
  • Resolution: Wait and see if the issue continues with the next attempt. If it does, communicate with the subscriber via other channels to verify number is accurate and able to receive SMS communications.

Investigation tips

Here are some questions whose answers can help you identify the source of any delivery issues:

• What is the error code for the recipient?
• Is there a trend in the error code/carrier/region or is it local to individual recipients?
• What is different with this send than previous sends?
• Is the content in alignment with regional regulations?
• Is the content longer than 320 characters?
• Are shared domains being used in links?
• Are emojis or irregular capitalization/punctuation used in the content?
• Is your sender ID up-to-date?
• Have you made any changes to your number or sender ID recently?
• Have these recipients expressly opted in?
• Have these recipients received clear opt-out directions?
• Are opt-out requests being honored?
• Are you seeing regular engagements that meet our advised thresholds?

Delivery speed issues

The delivery speed or messages per second (MPS) that can be delivered from your phone number is limited and dependent on your Trust Score and the declared use-case categorization of your company/SMS traffic.

For details on what your limit is based on Trust Score and Categorization, read this Twilio article.