List available platform domains

Returns the platform-managed domains available for inbox creation, filtered by your plan:

• Free / Developer / Startup — free-tier domains only.
• Growth / Enterprise — free-tier + pro-tier domains.

Results are cached for up to 5 minutes. New domains appear automatically without requiring a code change on your side.

Tags on each domain:

• new — recently added domain, shown for ~30 days.
• popular — high-traffic domain.

Domains expiring within 30 days include expires_at and expires_in_days as a heads-up to migrate inboxes. Healthy domains omit these fields entirely to keep the payload lean.

Custom domains (domains you own and verified) are managed via GET /v1/custom-domains — this endpoint only returns platform domains.