Populated only on message.failed.
| Name | Type | Description | Notes |
|---|---|---|---|
| code | Integer | [optional] | |
| title | String | [optional] | |
| message | String | [optional] | |
| explanation | String | Plain-language translation of `code` (e.g. for 131026, that the recipient has likely opted out of marketing messages while utility templates are unaffected). Null for unmapped codes; fall back to title/message. | [optional] |