diff --git a/localstack-core/localstack/openapi.yaml b/localstack-core/localstack/openapi.yaml
index f1932daf0a179..1a78bfe3d0e28 100644
--- a/localstack-core/localstack/openapi.yaml
+++ b/localstack-core/localstack/openapi.yaml
@@ -158,7 +158,7 @@ components:
           additionalProperties: false
           properties:
             html_part:
-              type: string
+              type: [string, 'null']
             text_part:
               type: string
           required:
diff --git a/localstack-core/localstack/services/ses/models.py b/localstack-core/localstack/services/ses/models.py
index 778f75dcc484a..2560f872410da 100644
--- a/localstack-core/localstack/services/ses/models.py
+++ b/localstack-core/localstack/services/ses/models.py
@@ -4,7 +4,7 @@
 
 
 class SentEmailBody(TypedDict):
-    html_part: str
+    html_part: str | None
     text_part: str