报表优化，

邮件内容验证

modules/i3plus-core-apiservice/src/main/java/cn/estsh/i3plus/core/apiservice/util/MailUtil.java

@@ -200,6 +200,9 @@ public class MailUtil {
             msg.setSubject( MimeUtility.encodeText(this.title, MimeUtility.mimeCharset("gb2312"), null));
             msg.setSubject(this.title);
 
+            // 消息主体内容 处理
+            this.content = this.content == null ? "" : this.content;
+
             msg.setContent(this.content, this.content_type);
 
             msg.saveChanges();