diff --git a/public/script.js b/public/script.js
index de853be..1104243 100644
--- a/public/script.js
+++ b/public/script.js
@@ -270,6 +270,13 @@ document.getElementById('smtpForm').addEventListener('submit', async function (e
     const formData = new FormData(this);
     const data = Object.fromEntries(formData.entries());
 
+    // Trim all string values to prevent copy-paste whitespace issues
+    Object.keys(data).forEach(key => {
+        if (typeof data[key] === 'string') {
+            data[key] = data[key].trim();
+        }
+    });
+
     try {
         const response = await fetch('/api/test-smtp', {
             method: 'POST',
@@ -365,6 +372,13 @@ document.getElementById('autoTestBtn').addEventListener('click', async function
     const formData = new FormData(form);
     const data = Object.fromEntries(formData.entries());
 
+    // Trim all string values
+    Object.keys(data).forEach(key => {
+        if (typeof data[key] === 'string') {
+            data[key] = data[key].trim();
+        }
+    });
+
     // Only need host, user, pass, from, to for auto test
     const autoTestData = {
         host: data.host,