Added a warning about Outbox storage format and clarified partition key behavior for Azure Table (#7820)

* Added a warning about Outbox storage format and clarified partition key behavior.

Added a warning about Outbox storage format and clarified partition key behavior.

* Tweaks

---------

Co-authored-by: Andreas Öhlund <[email protected]>

Author: danielmarbach

persistence/azure-table/index.md

@@ -51,4 +51,11 @@ partial: saga-property-types
 Saga correlation property values are subject to the underlying Azure Storage table `PartitionKey` and `RowKey` restrictions:
 
 * Up to 1KB in size
-* Cannot contain [invalid characters](https://docs.microsoft.com/en-us/rest/api/storageservices/Understanding-the-Table-Service-Data-Model#tables-entities-and-properties)
+* Cannot contain [invalid characters](https://docs.microsoft.com/en-us/rest/api/storageservices/Understanding-the-Table-Service-Data-Model#tables-entities-and-properties)
+
+## Outbox
+
+### Storage format
+
+> [!WARNING]
+> The default partition key, when not explicitly set, does not separate Outbox rows by endpoint name. Because of that, multiple logical endpoints cannot share the same table since [message identities are not unique across endpoints from a processing perspective](/nservicebus/outbox/#message-identity). Either separate different endpoints into different tables or [override the partition key](transactions.md).