21738: Brand Registration Failure: 2FA Email Undeliverable

This error means the Authentication+ verification email for your A2P 10DLC brand contact could not be delivered. Your brand contact must receive and complete this 2FA step before brand registration can continue.

• The brand_contact_email value is invalid or contains a typo.
• The mailbox is inactive or cannot receive external email.
• The recipient's email server rejected the verification message.

• Confirm that the brand contact email is correct, active, and able to receive external messages.
• If the email address is incorrect, update brand_contact_email in the associated us_a2p_messaging_profile_information bundle for the brand.
• If this is a new brand registration, trigger Authentication+ again after updating the email address by creating a new Brand 2FA verification request.
• If the brand contact still did not receive the email, resend the verification email from Console under Messaging > Regulatory Compliance > Brands.
• If you are re-verifying an existing brand, update brand_contact_email, move the associated bundle to pending-review, and call the brand update endpoint.

• Troubleshooting A2P 10DLC Standard and Low Volume Standard brands
• A2P 10DLC Brand 2FA Verification Resource
• Gather the required business information for A2P 10DLC