diff --git a/packages/playground/src/components/smtp_server.vue b/packages/playground/src/components/smtp_server.vue
index f01dc9b664..3f91660dda 100644
--- a/packages/playground/src/components/smtp_server.vue
+++ b/packages/playground/src/components/smtp_server.vue
@@ -21,6 +21,7 @@
         :value="$props.modelValue.username"
         :rules="[
           validators.required('Email is required.'),
+          validators.isEmail('Please provide a valid email address.'),
           v => {
             return isDiscourse ? undefined : validators.isEmail('Please provide a valid email address.')(v);
           },