Try this:
using (MailMessage emailMessage = new MailMessage())
{
emailMessage.From = new MailAddress("account2@gmail.com", "Account2");
emailMessage.To.Add(new MailAddress("account1@gmail.com", "Account1"));
emailMessage.Subject = "SUBJECT";
emailMessage.Body = "BODY";
emailMessage.Priority = MailPriority.Normal;
using (SmtpClient MailClient = new SmtpClient("smtp.gmail.com", 587))
{
MailClient.EnableSsl = true;
MailClient.Credentials = new System.Net.NetworkCredential("account2@gmail.com", "password");
MailClient.Send(emailMessage);
}
}
I added the port to the smtp client and enabled SSL. If port 587 doesn't work, try port 465.