audience unique identifier

uuid of a campaign on this audience — its channel is resolved server-side and used to filter contactable recipients. Excludes talent Hire has suppressed, or that opted out, on that channel. This filter narrows results only when channel enforcement is enabled for the tenant; omitting the parameter always returns every visible recipient. When channel enforcement is disabled for the tenant, the campaign is never looked up — an unknown or mismatched campaignUuid returns every visible recipient instead of a 404.