Sending mail in asp.net using gmail gateway

using System.Net.Mail;

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public string SendMail(string uname,string password, string To, string Subject, string Body)
    {
        string fromid = uname;
        string mypass = password;

        try
        {
            //Create Mail Message Object with content that you want to send with mail.
            MailMessage MyMailMessage = new MailMessage(fromid, To, Subject, Body);
            MyMailMessage.IsBodyHtml = true;
            //Proper Authentication Details need to be passed when sending email from gmail
            System.Net.NetworkCredential mailAuthentication = new System.Net.NetworkCredential(fromid, mypass.ToString());
            //Smtp Mail server of Gmail is "smpt.gmail.com" and it uses port no. 587
            //For different server like yahoo this details changes and you can
            //get it from respective server.
            System.Net.Mail.SmtpClient mailClient = new System.Net.Mail.SmtpClient("smtp.gmail.com", 587);
            //Enable SSL
            mailClient.EnableSsl = true;
            mailClient.UseDefaultCredentials = false;
            mailClient.Credentials = mailAuthentication;
            mailClient.Send(MyMailMessage);

            return "Mail Sent";
        }
        catch (SmtpException ex)
        {
            string error = ex.ToString();
            if (error.Contains("The remote name could not be resolved: 'smtp.gmail.com'"))
            {

                return "No Connection";

            }
            else if (error.Contains("The server response was: 5.5.1 Authentication Required"))
            {

                return "Username Password Missmatch";
            }
            else
            {

                return "Mail Not Sent";
            }

        }
    }