Preview how a draft campaign looks in real inboxes by sending a test to up to five recipient email addresses. An optional contact_uid personalizes those emails and does not add a sixth recipient.

For regular campaigns, requires filled html, subject, and from address on the campaign. For A/B campaigns, require variant_id (regular/HTML variants only — plain-text variants return 422) and those fields on the selected variant. Allowed while under review. Subject to daily test-email limits on the account. Returns 422 for invalid status/content, recipients, or when limits are exceeded.