The next tool you need to make a program send an SMS message is a method for sending an email. In recent years this has become harder because there are few email providers willing to let you send anonymous emails. Now to send an email, you need to create a NetworkCredential object that specifies your email server, user name, and password.

This example uses the following SendEmail method to send an email.

using System.Net;
using System.Net.Mail;

// Send an email message.
private void SendEmail(string to_name, string to_email,
    string from_name, string from_email,
    string host, int port, bool enable_ssl, string password,
    string subject, string body)
{
    // Make the mail message.
    MailAddress from_address = new MailAddress(from_email, from_name);
    MailAddress to_address = new MailAddress(to_email, to_name);
    MailMessage message = new MailMessage(from_address, to_address);
    message.Subject = subject;
    message.Body = body;

    // Get the SMTP client.
    SmtpClient client = new SmtpClient()
    {
        Host = host,
        Port = port,
        EnableSsl = enable_ssl,
        UseDefaultCredentials = false,
        Credentials = new NetworkCredential(from_address.Address, password),
    };

    // Send the message.
    client.Send(message);
}

The method creates MailAddress objects to represent the From and To email addresses. You can use strings for these when you make the MailMessage but then you can't associate a human-friendly name (like "Rod Stephens") with the email addresses.

Next the program creates a MailMessage, passing its constructor the From and To addresses. The code then sets the MailMessage's Subject and Body fields.

The method then creates an SmtpClient object. It sets the client's host and port so it knows where to send the email. The method sets the EnableSsl property according to the value it was passed as a parameter. If your email server uses SSL (Secure Sockets Layer--Gmail uses this), check the box on the form so this is set to true.

The code also sets UseDefaultCredentials to false and sets the client's Credentials property to a new NetworkCredential object containing your email user name and password.

Finally the method calls the SmtpClient's Send method to send the email.

The System.Net.Mail.MailMessage class supports some other features that you might want to use. For example, it has CC and Bcc properties that let you send courtesy copies and blind courtesy copies. The version shown here is good enough for the next post, which sends an SMS message.

The following code shows how the program calls the SendEmail method.

// Send the message.
private void btnSend_Click(object sender, EventArgs e)
{
    try
    {
        SendEmail(txtToName.Text, txtToEmail.Text,
            txtFromName.Text, txtFromEmail.Text,
            txtHost.Text, int.Parse(txtPort.Text),
            chkEnableSSL.Checked, txtPassword.Text,
            txtSubject.Text, txtBody.Text);
        MessageBox.Show("Message sent");
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

This code simply calls SendEmail passing it the values you entered on the form.

Note that the form's initial values for host and port (smtp.gmail.com and 587) work for Gmail. If you want to use some other email host, you'll need to change those values.

The next post will bring together the results of this post and the previous JSON posts to send an SMS message.