diff --git a/documentation/modules/ROOT/pages/transformations/mongodb-outbox-event-router.adoc b/documentation/modules/ROOT/pages/transformations/mongodb-outbox-event-router.adoc
index 0ee562b98..da0d1a3c7 100644
--- a/documentation/modules/ROOT/pages/transformations/mongodb-outbox-event-router.adoc
+++ b/documentation/modules/ROOT/pages/transformations/mongodb-outbox-event-router.adoc
@@ -338,6 +338,7 @@ The SMT automatically filters out `DELETE` operations on an outbox collection.
 |`_id`
 |Collection
 |Specifies the outbox collection field that contains the unique event ID.
+This ID will be stored in the emitted event's headers under the `id` key.
 
 |[[mongodb-outbox-event-router-property-collection-field-event-key]]<<mongodb-outbox-event-router-property-collection-field-event-key, `collection.field.event.key`>>
 |`aggregateid`
@@ -358,6 +359,7 @@ The SMT automatically filters out `DELETE` operations on an outbox collection.
 |`aggregateid`
 |Collection
 |Specifies the outbox collection field that contains the payload ID.
+This ID will be used as the emitted event's key.
 
 |[[mongodb-outbox-event-router-property-collection-expand-json-payload]]<<mongodb-outbox-event-router-property-collection-expand-json-payload, `collection.expand.json.payload`>>
 |`false`
diff --git a/documentation/modules/ROOT/pages/transformations/outbox-event-router.adoc b/documentation/modules/ROOT/pages/transformations/outbox-event-router.adoc
index 9f9c9e311..707837fbf 100644
--- a/documentation/modules/ROOT/pages/transformations/outbox-event-router.adoc
+++ b/documentation/modules/ROOT/pages/transformations/outbox-event-router.adoc
@@ -339,6 +339,7 @@ The SMT automatically filters out `DELETE` operations on an outbox table.
 |`id`
 |Table
 |Specifies the outbox table column that contains the unique event ID.
+This ID will be stored in the emitted event's headers under the `id` key.
 
 |[[outbox-event-router-property-table-field-event-key]]<<outbox-event-router-property-table-field-event-key, `table.field.event.key`>>
 |`aggregateid`
@@ -359,6 +360,7 @@ The SMT automatically filters out `DELETE` operations on an outbox table.
 |`aggregateid`
 |Table
 |Specifies the outbox table column that contains the payload ID.
+This ID will be used as the emitted event's key.
 
 |[[outbox-event-router-property-table-expand-json-payload]]<<outbox-event-router-property-table-expand-json-payload, `table.expand.json.payload`>>
 |`false`