Delivery attempts so far; at the configured cap the relay dead-letters the row.
Correlation id of the request that enqueued this event, or null for worker-born events. Transport provenance lives here because the relay reads the envelope in another process; domain facts about the posting stay in its meta.
Why the relay gave up, set when the row goes 'dead'; null otherwise.
'pending' is the only status claimBatch ever hands back; 'relayed' and 'dead' are terminal.
One stored outbox row: an event plus the bookkeeping for delivering it (see OutboxStore).