diff --git a/types.go b/types.go
index a68290d..295ea18 100644
--- a/types.go
+++ b/types.go
@@ -437,7 +437,8 @@ type (
 
 	// SenderBatchHeader struct
 	SenderBatchHeader struct {
-		EmailSubject string `json:"email_subject"`
+		EmailSubject  string `json:"email_subject"`
+		SenderBatchID string `json:"sender_batch_id,omitempty"`
 	}
 
 	// ShippingAddress struct