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Error 21610

ERROR - 21610

Attempt to send to unsubscribed recipient

You have attempted to send to a 'To' number that has replied with "STOP" to one of your previous messages. The person you are trying to message has opted out of messages from your message sender or Messaging Service.

You have attempted to message a 'To' number that has replied with "STOP" to one of your previous messages. You will not be able to send to the phone number specified in the 'To' parameter until the subscriber identified by the phone number has responded with "START".

More information about how Twilio handles Opt-Outs.

Possible Causes

  • The end user handset has responded with a "STOP" or other opt-out keywords.
  • The recipient may not have opted into your messages. Please ensure you have received consent to message this recipient. Please read these guidelines to understand messaging opt-in requirements and best practices.

Possible Solutions

  • Consider removing this phone number from your list of recipients for a better experience for your end users and your brand.
  • Request the recipient to resubscribe by texting in "START" or other opt-in keywords to your Twilio sender.
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