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Best Practices for SMS Deliverability and Avoiding SMS Restrictions

Monitoring Error and Opt-out Rates​

At Stack, we prioritize helping you deliver trusted communications. To ensure your messages reach their destination and avoid any carrier blocks or suspensions, we actively monitor your account's delivery rates. Here’s how we manage this process:

Notifications and Restrictions​

  • Violation Email: You'll receive an email notification if your subaccount reaches an error rate of 8% or an opt-out rate of 2%.
  • Temporary Account Restriction: If the error rate hits 12.5% or the opt-out rate reaches 3%, a suspension email will be sent. During this suspension, all outbound SMS will fail until 00:00 AM UTC.

Responding to a Violation Email​

  1. Pause Communications: Stop all workflows, campaigns, triggers, and bulk actions to contacts who haven't explicitly opted in.
  2. Customize Opt-Out Language: Ensure your messages include opt-out instructions and a clear Sender ID to prevent them from being flagged.
  3. Avoid Bulk Messaging: Discuss with your team to prevent sending bulk communications or cold prospecting campaigns until the issue is resolved.

Understanding Error and Opt-out Rates​

  • High Opt-Out Rate: Indicates recipients are objecting to your messages, possibly marking them as spam. Aim for an opt-out rate between 0-1%. A rate of 2% will result in a 24-hour suspension.
  • High Delivery Error Rate: Suggests messages are sent to inactive numbers or non-SMS-capable devices. Maintain an error rate between 0-6%. A rate of 12% will lead to a 24-hour suspension.

Lifting a Suspension​

Suspensions are automatically lifted after 24 hours. For permanent suspensions, refer to the article on account suspension resolution.

Preventing Future SMS Suspensions​

To maintain a healthy delivery rate, consider the following best practices:

  1. Include Opt-Out Instructions: Always add "Reply STOP to unsubscribe" in your initial SMS to new contacts.
  2. Identify Yourself: Include sender information in your first message to new contacts.
  3. Avoid SMS to Landlines: Use the Number Validation feature to check numbers before sending messages.
  4. Use Full URLs: Avoid public URL shorteners like bit.ly; use the full link instead.
  5. Register Your Business: Ensure your Business Profile, A2P Brand, and campaigns are registered for better message delivery. Learn more about business registration.

Additional Tips​

  • Consent in Web Forms: Include a checkbox for consent in web forms to ensure leads opt-in properly.
  • Source Information: Mention how the lead opted in your first message.
  • Double Opt-In: Encourage contacts to confirm their subscription via SMS or web form.

For further guidance, refer to our Messaging Policy for comprehensive support on maintaining compliance and optimizing deliverability.