Can't Send Emails From my Website

Question

Here I am in a strange situation. When I send the email from localhost it is working fine but when I upload the page to the server and try to send email, I get the following error

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

I'm displaying the error message in a label for testing purpose and the try is also misplaced I know, I will set it later.

the code I am using is

 if (Page.IsValid)
    {
try
            {
            StringBuilder message = new StringBuilder();
            message.Append("Hello My Name is ");
            message.Append(txtName.Text);
            message.AppendLine();
            message.AppendLine("My Contact Number " + txtContactNumber.Text.ToString());
            message.AppendLine();
            message.AppendLine();
            message.AppendLine("My Email Id Is " + txtFromEmailAddress.Text.ToString());
            message.AppendLine();
            message.Append(txtEmailBody.Text);


        MailMessage mailMessage = new MailMessage("xxx@gmail.com", "yyy@gmail.com");
        mailMessage.Subject = "New Client Query";
        mailMessage.Body = message.ToString();

        SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 25);
        //smtpClient.UseDefaultCredentials = true;
        smtpClient.Credentials = new System.Net.NetworkCredential()
        {
            UserName = "xxx@gmail.com",
            Password = "password"
        };
        smtpClient.EnableSsl = true;

            smtpClient.Send(mailMessage);


        txtContactNumber.Text = "";
        txtFromEmailAddress.Text = "";
        txtName.Text = "";
        txtEmailBody.Text = "";
        lblEmailStatus.Text = "Email Sent Successfully.";
        lblEmailStatus.ForeColor = System.Drawing.Color.Yellow; 
        }
        catch(Exception ex)
        {
            lblEmailStatus.Text = ex.Message + " <br> " + ex.Source;
        }
    }
    else
    {

        lblEmailStatus.Text = "Error!   Email Not Sent ";
        lblEmailStatus.ForeColor = System.Drawing.Color.Yellow;
    }

I have googled for a couple of hours and checked links at this site as well but I still cant figure it out.

Now I request you guys here if any one have any solutions / hint.

Answer 1

i got the reason finally .

the email i was sending emails from was kind of hacked some days before and for the security reasons google team had kind of marked my email as unsecure . i changed the emails address and it is working fine thanks you all.

Answer 2

Try this

    public string SendEmailTest(String EmailMessage, String FromMail, String MailPassword, String MailServer, String To, String CC, String BCC, String DisplayName, String Subject, String Attachment)
    {
        try
        {
            SmtpClient smtpClient = new SmtpClient();

            MailMessage message = new MailMessage();

            MailAddress fromAddress;

            fromAddress = new MailAddress(FromMail);

            smtpClient.Host = MailServer;
            smtpClient.Port = 25;

            System.Net.NetworkCredential SMTPUserInfo = new System.Net.NetworkCredential(FromMail, MailPassword);
            smtpClient.UseDefaultCredentials = false;
            smtpClient.Credentials = SMTPUserInfo;

            message.From = fromAddress;

            message.To.Add(new MailAddress(To, DisplayName));
            if (CC != "")
                message.CC.Add(new MailAddress(CC, DisplayName));
            if (BCC != "")
                message.Bcc.Add(new MailAddress(BCC, DisplayName));

            message.Subject = Subject;

            message.IsBodyHtml = true;
            message.Body = EmailMessage;

            if (Attachment != "")
                message.Attachments.Add(new Attachment(Attachment));

            message.Priority = MailPriority.High;

            smtpClient.Send(message);
            return "SendEmail";
        }
        catch (Exception ex)
        {
            return "Email :" + ex;
        }

    }

Answer 3

Based on the Google Gmail Documentation it would appear that the Port should be 587 not 25. I found a few other questions that seem to be related here and here.

SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
client.UseDefaultCredentials = false;