E04009 — OnboardingRecipientNotAllowed

Sends from the shared onboarding domain can only go to verified members of your workspace.

• HTTP status: 422
• Type: validation_error
• Name: OnboardingRecipientNotAllowed

What to do

Add and verify a custom sending domain to send to any recipient, then retry.

Operations that resolve this:

• List sending domains
• Create a sending domain
• Verify a domain

Related

• E04xxx — Email sending & delivery: every code in this range
• Errors: the full wire contract, status mapping, and error catalog
• Error handling: branching on type and code, validation details, and vendor_code