**Source URL:** https://general.veevavault.dev/quality/mdl/component-types/messagedeliveryeventhandler.md

# Messagedeliveryeventhandler

**Class: ** `code`

Spark message delivery event handlers provide a way to handle undelivered Spark messages. For example, implement `MessageDeliveryEventHandler` in your custom code and add it to an <em>Outbound Queue</em>. When an undeliverable message is encountered, Vault executes the logic coded in the handler.

Learn about <a href="/sdk/#Message_Delivery_Event_Handler" target="_blank">Spark Message Delivery Event Handlers</a>.

| Attribute | Metadata | Description |
| --- | --- | --- |
| label | Type: StringMax length: 60 | UI-friendly string in the Vault’s base language. |
| active | Type: Boolean | Indicates whether the component is active. |
| checksum | Type: StringMax length: 1500 | Used to check data for errors. |
| source_code | Type: SdkCodeMax length: 1048576 | The source of this Spark message delivery event handler and code used to create and edit metadata.Custom means this handler was developed with the Vault Java SDK. |

### Supported Operations {#supported-operations}

| Operation | Support |
| --- | --- |
| Create | No |
| Recreate | No |
| Alter | No |
| Drop | No |
| Rename | No |
| Describe | No |
| Generate Recreate | No |
| Queryable | Yes |


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