**Source URL:** https://limited.veevavault.dev/qualityone/mdl/component-types/messagedeliveryeventhandler

# 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 *Outbound Queue*. When an undeliverable message is encountered, Vault executes the logic coded in the handler.

Learn about [Spark Message Delivery Event Handlers](/sdk/#Message_Delivery_Event_Handler).

| Attribute | Metadata | Description |
| --- | --- | --- |
| `label` | Type: String Max length: 60 | UI-friendly string in the Vault’s base language. |
| `active` | Type: Boolean | Indicates whether the component is active. |
| `checksum` | Type: String Max length: 1500 | Used to check data for errors. |
| `source_code` | Type: SdkCode Max 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

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

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