The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required.

See more:

ASP.NET

Hi
I have developed the code for sending an email for contact us page.

i have got the following error,
Error:
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required.

Can anyone help me to solve this..whats wrong in my code?

Here is my code..

        MailMessage msg = new MailMessage();
        msg.SubjectEncoding = System.Text.Encoding.UTF8;
        msg.IsBodyHtml = true;
        msg.BodyEncoding = System.Text.Encoding.UTF8;
        msg.Priority = MailPriority.High;
        string fromaddrs = @"domain mail id";
        string toaddrs = @"thendral.marlen@gmail.com";
        msg.From = new MailAddress(fromaddrs);
        msg.To.Add(toaddrs);
        msg.Subject = "VelFlora_Feedback";
        string body = "<table width="527" border="0" cellspacing="1" cellpadding="1">" +
                        "<tr>" +
                            "<td width="20%" height="20"><b>FirstName:</b> </td>" +
                            "<td width="80%">" + fname + "</td>" +
                        "</tr>" +
                        "<tr>" +
                            "<td width="20%" height="20"><b>LastName:</b> </td>" +
                            "<td width="80%">" + lname + "</td>" +
                        "</tr>" +
                        "<tr>" +
                            "<td height="20"><b>ContactNo:</b></td>" +
                            "<td>" + phone + "</td>" +
                        "</tr>" +
                        "<tr>" +
                            "<td height="20"><b>EmailID:</b></td>" +
                            "<td>" + email + "</td>" +
                        "</tr>" +
                        "<tr>" +
                            "<td width="20%" height="20"><b>CompanyName:</b> </td>" +
                            "<td width="80%">" + com_name + "</td>" +
                        "</tr>" +
                         "<tr>" +
                            "<td width="20%" height="20"><b>CompanyWebsite:</b> </td>" +
                            "<td width="80%">" + com_site + "</td>" +
                        "</tr>" +
                         "<tr>" +
                            "<td width="20%" height="20"><b>Country:</b> </td>" +
                            "<td width="80%">" + country + "</td>" +
                    "</tr>" +
                          "<tr>" +
                            "<td height="20"><b>ContactAddress:</b></td>" +
                            "<td>" + address + "</td>" +
                        "</tr>" +
"<tr>" +
                            "<td height="20"><b>Queries:</b></td>" +
                            "<td>" + query + "</td>" +
                        "</tr>" +
                        "</table>";

        msg.Body = body.ToString();
        SmtpClient client = new SmtpClient();
        client.Credentials = new System.Net.NetworkCredential(fromaddrs, "password");
        client.Port = 587;
        client.Host = "smtp.gmail.com";
        client.EnableSsl = true;
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        try
        {
            client.Send(msg);
            return 1;

        }
        catch (Exception ex1)
        {
            return -1;
        }

[edit]Code block added, HTML characters encoded - OriginalGriff[/edit]