I never realized this but you can set the default SMTP information in the .config file (Thanks Viktar!). This applies to the new System.Net.Mail.* classes (Not the deprecated System.Web.Mail.* classes). MSDN defines the elements here and here.

      <smtp deliveryMethod="network" 
         from="">appointments@TrepanationNation.com"> <network host="smtp.TrepanationNation.com"
         port="25" defaultCredentials="true"/> smtp> mailSettings> system.net>

The code is the same but you no longer have to specify the from and SMTP server details:

using (MailMessage message = new MailMessage())
    message.IsBodyHtml = true;
    message.Subject = "Trepanation Appointment";
    message.Body = @"This confirms your 
        Trepanation appointment this Friday.";
    SmtpClient mailClient = new SmtpClient();