Source note · Troubleshooting business SMS that is not delivered
A recipient blocked under 21610 regains delivery by texting START or another opt-in keyword to the sender; the sending business cannot clear it on the recipient's behalf per the documented process.
Checked 2026-10-02
- Vendor
- Twilio
- Product
- Twilio Programmable Messaging
- Subsystem
- opt-out handling
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- 21610: Attempt to send to unsubscribed recipient — Twilio · tier 2 current vendor documentation · Possible solutions section
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting business SMS that is not delivered: source note business-sms-delivery-troubleshooting-err-21610-start-resub. WarmTransfer. https://warmtransfer.net/knowledge/claims/business-sms-delivery-troubleshooting-err-21610-start-resub
BibTeX
@misc{warmtransfer-claim-business-sms-delivery-troubleshooting-err-21610-start-resub,
title = {Troubleshooting business SMS that is not delivered: source note business-sms-delivery-troubleshooting-err-21610-start-resub},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/business-sms-delivery-troubleshooting-err-21610-start-resub},
note = {Source note business-sms-delivery-troubleshooting-err-21610-start-resub, checked 2026-10-02}
}