diff --git a/ruoyi-oa/src/main/java/com/ruoyi/oa/utils/EmailUtil.java b/ruoyi-oa/src/main/java/com/ruoyi/oa/utils/EmailUtil.java
index ae63a35..ab6b2cb 100644
--- a/ruoyi-oa/src/main/java/com/ruoyi/oa/utils/EmailUtil.java
+++ b/ruoyi-oa/src/main/java/com/ruoyi/oa/utils/EmailUtil.java
@@ -357,12 +357,19 @@ public class EmailUtil {
     }
 
     /**
-     * 下载网络文件到本地临时文件
+     * 下载网络文件到本地临时文件，保留原始文件后缀
      * @param url 文件的http/https链接
      * @return 本地临时文件
      */
     public static File downloadUrlToTempFile(String url) throws Exception {
-        File tempFile = File.createTempFile("mail_attach_", null);
+        // 提取文件名和后缀
+        String fileName = url.substring(url.lastIndexOf('/') + 1);
+        String suffix = "";
+        int dotIdx = fileName.lastIndexOf('.');
+        if (dotIdx != -1) {
+            suffix = fileName.substring(dotIdx);
+        }
+        File tempFile = File.createTempFile("mail_attach_", suffix);
         try (java.io.InputStream in = new java.net.URL(url).openStream();
              java.io.OutputStream out = new java.io.FileOutputStream(tempFile)) {
             byte[] buffer = new byte[8192];