Fix Twilio 21610 in GoHighLevel

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Fix Twilio Error 21610 in GoHighLevel

If you manage client communication across tools like ClickUp and GoHighLevel, you may sometimes see Twilio error 21610 when sending SMS. This error means Twilio has blocked your message because the recipient has opted out or a blacklist rule prevents delivery. This step-by-step guide shows you exactly how to resolve Twilio error 21610 inside your GoHighLevel account while staying compliant with carrier and Twilio policies.

The instructions in this article are based on Twilio's behavior and how the integration works inside the HighLevel platform, which powers GoHighLevel sub-accounts and phone number settings.

What Twilio Error 21610 Means in GoHighLevel

Twilio error 21610 occurs when a message you send through GoHighLevel is blocked because the from/to pair violates a blacklist rule. In most cases, this happens after a contact has replied with a standard opt-out keyword such as:

  • STOP
  • STOPALL
  • UNSUBSCRIBE
  • CANCEL
  • END
  • QUIT

Once Twilio registers one of these opt-out messages from a contact, it will no longer deliver messages from the same sending number to that specific recipient number. Any further attempts from GoHighLevel to send SMS to that contact will trigger error 21610.

This is a carrier and compliance safeguard and cannot be bypassed by simply resending the same text or switching workflows inside GoHighLevel.

How GoHighLevel Handles Twilio Opt-Out Rules

When you send SMS through GoHighLevel, the platform uses Twilio's infrastructure under the hood. Twilio automatically enforces its blacklist rules according to carrier regulations. This behavior applies regardless of your pipeline, campaign, or automation settings inside the GoHighLevel dashboard.

Key points about this enforcement:

  • The opt-out is stored by Twilio per from number and to number combination.
  • Once a contact opts out, Twilio blocks further SMS from that specific GoHighLevel/Twilio number.
  • Changing workflows or resending campaigns inside GoHighLevel will not lift the block.

To restore messaging, the contact must explicitly opt back in following Twilio's re-subscription standards.

Step-by-Step: Fix Error 21610 for GoHighLevel Users

Follow these steps to properly resolve Twilio error 21610 within your GoHighLevel environment.

Step 1: Confirm the Error in GoHighLevel

  1. Open your Conversations or corresponding SMS log inside GoHighLevel.
  2. Locate the failed message that shows the delivery error.
  3. Check the error details or logs. If you see 21610 with a note about a blacklist rule, you are dealing with an opt-out issue.

At this point, do not keep retrying the same SMS, because Twilio will continue to block it until the recipient opts back in.

Step 2: Understand Why the GoHighLevel Message Was Blocked

The message has been blocked because the contact previously sent an opt-out keyword to your Twilio number managed by GoHighLevel. Typical scenarios include:

  • A lead replied STOP to one of your previous campaigns.
  • A customer texted CANCEL after receiving appointment reminders.
  • Somebody responded QUIT to unsubscribe from your SMS marketing.

This opt-out action is recorded directly by Twilio, not just within GoHighLevel, so it applies to all future texts sent from the same number to that contact.

Step 3: Ask the Contact to Opt Back In

To send SMS again via GoHighLevel, the contact must send a clear opt-in message from their device to your Twilio number. According to Twilio's rules, the contact should text a message such as:

  • START
  • YES
  • UNSTOP

These replies tell Twilio to remove the block for that specific from/to pair. You can reach out to the contact using another channel to request this opt-in, for example:

  • Email
  • Phone call
  • Social media message
  • In-person request

Once they send START, YES, or UNSTOP to your GoHighLevel number, Twilio should allow future SMS traffic from that number to the contact.

Step 4: Resend the Message from GoHighLevel

  1. After the contact has successfully opted back in, return to the Conversations section in GoHighLevel.
  2. Compose a new SMS to the same contact from the same number.
  3. Send a short confirmation message, such as: "You're now opted back in for SMS updates."
  4. Verify that the message status is now delivered rather than failed with error 21610.

If delivery is successful, you can resume your normal automations, campaigns, and appointment reminders for that contact in GoHighLevel.

Important Compliance Notes for GoHighLevel SMS Users

Because GoHighLevel relies on Twilio's messaging infrastructure, you must follow Twilio and carrier compliance rules at all times. This includes respecting opt-out and opt-in keywords. Avoid:

  • Attempting to circumvent the block by changing phone numbers without consent.
  • Manually forcing messages through alternative systems when a user has already opted out.
  • Ignoring STOP or similar keywords inside your GoHighLevel conversation history.

Instead, always obtain explicit consent and clearly explain what kind of SMS the contact will receive once they opt back in.

Best Practices to Prevent Error 21610 in GoHighLevel

Use these tips to reduce how often Twilio error 21610 appears inside GoHighLevel:

  • Set clear expectations in your first welcome message about how often you will text and what type of content you send.
  • Include opt-out instructions in your SMS, such as "Reply STOP to unsubscribe."
  • Keep frequency reasonable to minimize opt-outs triggered by message overload.
  • Segment your audiences so that contacts only receive relevant messages through GoHighLevel workflows.
  • Monitor unsubscribe trends to understand which campaigns generate more STOP replies.

Following these practices inside your GoHighLevel automations will keep your sender reputation healthier and improve overall deliverability.

Where to Learn More About Twilio and GoHighLevel

To dive deeper into the technical details of Twilio error 21610 and blacklist behavior, review the official HighLevel support documentation here: Twilio Error 21610 Support Article.

If you need professional help optimizing your GoHighLevel setup, including SMS workflows, automations, and multi-channel communication strategies, you can get expert consulting from Consultevo.

Summary: Handling 21610 Inside GoHighLevel

Twilio error 21610 inside GoHighLevel is a compliance safeguard triggered when a recipient has opted out and Twilio creates a blacklist rule for that from/to pair. You cannot fix it by resending the same message or changing campaigns alone. Instead, follow this sequence:

  1. Identify error 21610 in your GoHighLevel SMS logs.
  2. Recognize that the contact previously opted out with a STOP-type keyword.
  3. Ask the contact to opt back in by sending START, YES, or UNSTOP to your Twilio number.
  4. After the opt-in is confirmed, send a new message from GoHighLevel and verify delivery.

By respecting opt-out rules and following the proper re-subscription process, you can maintain compliant and reliable SMS communication through GoHighLevel.

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