diff --git a/javascript/src/iframe/viamapi-iframe.js b/javascript/src/iframe/viamapi-iframe.js
index f96df4b886d368a0c367c60f74d09178c170cc67..3e55cef7d07481916785eb83efbe2b48a53ae5ef 100644
--- a/javascript/src/iframe/viamapi-iframe.js
+++ b/javascript/src/iframe/viamapi-iframe.js
@@ -1566,7 +1566,7 @@ const connection = Penpal.connectToParent({
         parts = [];
       }
 
-      if (htmlBody) {
+      if (htmlBody || htmlBody === "") {
         if (typeof htmlBody !== "string") {
           throw new Error("htmlBody is not string"); // should not happen
         }
@@ -1583,7 +1583,7 @@ const connection = Penpal.connectToParent({
         });
       }
 
-      if (textBody) {
+      if (textBody || textBody === "") {
         if (typeof textBody !== "string") {
           throw new Error("textBody is not string"); // should not happen
         }