Introduction
SMS marketing is a powerful tool in Klaviyo, allowing brands to reach customers instantly. However, delivery failures can prevent messages from reaching recipients, affecting engagement and revenue.
If you’re experiencing Klaviyo SMS delivery issues, this guide will help you troubleshoot and resolve SMS not sending problems in Klaviyo and optimize SMS deliverability.
Answer: How to Fix Klaviyo SMS Delivery Issues?
SMS messages may fail due to carrier restrictions, compliance issues, incorrect formatting, or invalid recipient numbers. To resolve these issues:
Check SMS Compliance & Registration Status – Ensure your business is registered for SMS sending.
Verify Recipient Opt-In Status – Confirm contacts have opted in for SMS marketing.
Check for Carrier Filtering Issues – Carriers may block messages with certain keywords.
Ensure Correct Sender ID Setup – Verify your sending number is properly configured.
Review SMS Logs in Klaviyo – Identify error messages in the delivery report.
Check Number Formatting & Country Codes – Ensure correct phone number format.
Step-by-Step Guide to Fixing Klaviyo SMS Delivery Issues
1. Check SMS Compliance & Registration Status
Carriers block SMS messages if your business is not properly registered for sending.
How to Check Registration in Klaviyo:
Go to Klaviyo Dashboard → Click Account (top-right corner).
Select Settings → Click SMS Settings.
Check if your brand’s SMS registration is Pending, Approved, or Rejected.
Solution:
If your registration is pending, wait until it’s approved before sending SMS.
If your registration is rejected, reapply with correct details or contact Klaviyo support.
2. Verify Recipient Opt-In Status
SMS messages will not be sent if recipients haven’t opted in.
How to Check Opt-In Status:
Go to Lists & Segments → Select your SMS list.
Click on a subscriber profile → Check if “Subscribed to SMS” is True.
Solution:
If opt-in status is missing, confirm compliance with TCPA and GDPR and recollect consent via Klaviyo forms.
3. Check for Carrier Filtering Issues
Carriers may block SMS messages containing:
🚫 Spam-like content (excessive emojis, links, all-caps).
🚫 Restricted words (certain promotional terms).
How to Review Carrier Filtering Issues:
Go to Analytics → SMS Deliverability Reports.
Look for error messages like “Message Blocked by Carrier”.
Solution:
Avoid using spammy language in SMS.
Use Klaviyo's recommended formatting to pass carrier filters.
4. Ensure Correct Sender ID Setup
If your sending number is invalid, SMS will not be delivered.
How to Check Your Sender ID in Klaviyo:
Go to Account Settings → SMS.
Check if you’re using a dedicated number, shared short code, or toll-free number.
If using a toll-free number, ensure it’s verified with carriers.
Solution:
If using a toll-free number, register it with carrier verification.
If your sender ID is incorrect, update it and resend the SMS.
5. Review SMS Logs in Klaviyo
Klaviyo provides detailed SMS logs to track message delivery failures.
How to Access SMS Logs:
Go to Analytics → SMS Performance.
Click on a failed SMS campaign.
Look for error codes indicating why messages failed.
Solution:
Match error codes with Klaviyo’s help documentation for troubleshooting.
Resend messages after fixing the reported issue.
6. Check Number Formatting & Country Codes
SMS may fail if recipient phone numbers are not formatted correctly.
How to Validate Phone Numbers in Klaviyo:
Go to Profiles → Select a customer profile.
Ensure the phone number includes country code (e.g., +1 for US).
Solution:
If numbers are missing country codes, reformat them before resending SMS.
Ensure consistent formatting when importing numbers into Klaviyo.
Best Practices for Improving Klaviyo SMS Deliverability
✅ Register Your SMS Campaigns – Ensure compliance with carrier regulations.
✅ Use Verified Sending Numbers – Avoid using shared short codes for better deliverability.
✅ Check SMS Logs Regularly – Identify delivery failures early.
✅ Follow Carrier Guidelines – Avoid spammy content to prevent carrier filtering.
✅ Confirm Opt-In Compliance – Use double opt-in forms to collect consent.
Common Mistakes That Cause SMS Delivery Issues
🚫 Sending to Unsubscribed Contacts – SMS fails if recipients haven’t opted in.
🚫 Using Invalid Phone Numbers – Numbers missing country codes or formatted incorrectly.
🚫 Ignoring Carrier Filtering Rules – SMS blocked due to restricted words or spam-like content.
🚫 Using an Unverified Toll-Free Number – Some messages fail due to missing verification.
🚫 Exceeding SMS Sending Limits – Some regions have daily sending limits.
Conclusion
Fixing Klaviyo SMS delivery issues requires verifying opt-in status, checking sender ID, reviewing carrier restrictions, and formatting phone numbers correctly. By following this step-by-step guide, you can resolve SMS delivery problems in Klaviyo and improve SMS marketing performance.
📩 Need expert help fixing Klaviyo SMS deliverability? Let’s talk.
At Dispatch, we help brands resolve SMS issues and optimize SMS campaigns.
👉 Connect with Dispatch today to fix your Klaviyo SMS delivery issues.
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