Look up a message-id mapping

Map between the Message-ID you submitted and the Message-ID the upstream email provider assigned at delivery. Provide exactly ONE of the two query parameters:

• provider_message_id (alias: ses_message_id) — reverse lookup. You hold the provider-assigned id (e.g. from a reply's In-Reply-To header) and want the original id you generated. Returns at most one mapping.
• original_message_id — forward lookup. You hold the id you submitted and want the provider-assigned id(s). One-to-many: a send to N recipients yields N provider ids (one mapping per recipient).

Ids are accepted with or without angle brackets.

Mappings appear roughly 5 minutes after the send and are retained for 90 days. A mapping only exists for mail relayed through an upstream email provider — that is the mail whose Message-ID gets rewritten; mail sent directly from Winnr infrastructure keeps your original id and needs no mapping. An empty data array means no mapping (yet): either the send is less than ~5 minutes old, the mail did not relay through an upstream provider, or the mapping has aged out.