System.Net.Mail发送邮件失败所在

 /**//// <summary>
    /// 注册时发送用户帐号跟密码
    /// </summary>
    /// <param name="receiver">用户注册邮箱</param>
    /// <param name="username">用户名</param>
    /// <param name="password">用户密码明文</param>
    public bool Register(string receiver, string username, string password)
    ...{
        //System.Net.Mail.SmtpClient mail = new System.Net.Mail.SmtpClient();  
        //邮件发送时请确认服务的杀毒软件因素

        System.Net.Mail.SmtpClient client;
        client = new System.Net.Mail.SmtpClient("smtp.163.com");
        client.Timeout = 60000;
        
        //client.UseDefaultCredentials = false;
        
        client.UseDefaultCredentials = true;
        client.Credentials = new System.Net.NetworkCredential("[e-mail]", "123456");
        client.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
        System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
        message.SubjectEncoding = System.Text.Encoding.UTF8;
        message.BodyEncoding = System.Text.Encoding.UTF8;
        message.From = new System.Net.Mail.MailAddress("[e-mail]", "Andy Lu", System.Text.Encoding.UTF8);
        message.To.Add(new System.Net.Mail.MailAddress(receiver, username, System.Text.Encoding.UTF8));
        message.IsBodyHtml = false;
        message.Subject = "用户注册信息（软件项目网）";
        message.Body = username + "：您好！     欢迎您光临软件项目网[http://www.softprj.cn]！您注册的用户名是：" + username + "；密码是：" + password + "。     点此进入软件项目网：http://www.soft.cn";
        try
        ...{
            client.Send(message);
            return true;
        }
        catch
        ...{
            return false;
        }
    }

看了无数篇，检查了N次，原来是VirusScan 惹得祸！

关掉其“按访问扫描”一切OK
参考此篇http://blog.csdn.net/mengyao/archive/2007/08/16/1745836.aspx
转自：http://blog.csdn.net/mengyao/archive/2007/08/15/1743427.aspx