使用C#发送消息在本地有效，但在现场无声失败

我正在使用以下代码发送预订表单，但它在本地工作，但当我将其上线时，它失败了，并且不确定原因：

   protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void SendMail()
    {
        var sDate = startDate.Text;
        var eDate = endDate.Text;

        // Gmail Address from where you send the mail
        var fromAddress = "xxx@googlemail.com";
        // any address where the email will be sending
        var toAddress = "silverhillcattery@hotmail.co.uk";
        //Password of your gmail address
        const string fromPassword = "xxx";
        // Passing the values and make a email formate to display
        string subject = YourSubject.Text.ToString();
        string body = "From: " + YourName.Text + "\n";
        body += "Email: " + YourEmail.Text + "\n";
        body += "Contact Number: " + txtContactNumber.Text + "\n";
        body += "Subject: " + YourSubject.Text + "\n";
        body += "Question: \n" + Comments.Text + "\n";
        body += "Pet Name(s): \n" + txtPetName.Text + "\n";
        body += "Start Date: \n" + sDate + "\n";
        body += "End Date: \n" + eDate + "\n";

        // smtp settings
        var smtp = new System.Net.Mail.SmtpClient();
        {
            smtp.Host = "smtp.gmail.com";
            smtp.Port = 587;
            smtp.EnableSsl = true;
            smtp.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
            smtp.Credentials = new NetworkCredential(fromAddress, fromPassword);
            smtp.Timeout = 20000;
        }
        // Passing values to smtp object
        smtp.Send(fromAddress, toAddress, subject, body);
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            //here on button click what will done 
            SendMail();
            DisplayMessage.Text = "Thank you for contacting us we will get back to you shortly.  If you would like to talk to us, please call 0208 236 9572";
            DisplayMessage.Visible = true;
            YourSubject.Text = "";
            YourEmail.Text = "";
            YourName.Text = "";
            Comments.Text = "";
        }
        catch (Exception) { }
    }

它不会发送消息或显示“感谢您联系…”

这是网站www.silverhillcattery.co.uk

任何帮助都将不胜感激

更新：

我已按建议添加了错误消息，现在出现以下错误：

“SMTP服务器需要安全连接，或者客户端未经身份验证”

---

我将研究这个问题。

我只能猜测您的凭据在您的本地环境中有效，但在您的实时环境中无效。如果您的代码在发送时出现异常而失败，它将绕过显示代码，直接转到“捕获”代码

为了调试它，我会将send放在显示之后，以查看发生了什么，或者更恰当地修改catch（异常）以捕获错误并显示它

catch (Exception ex) 
{
          DisplayMessage.Text = "Failed to send email. Error = " + ex.message;
        DisplayMessage.Visible = true;
}