Send The Email Notification Without Using Credentials?

I have this code to send email notification in my page.

MailAddress to = new MailAddress("xxxxx@gmail.com");
MailAddress from = new MailAddress("xxx@gmail.com");
MailMessage message = new MailMessage(from, to);
message.Subject = "Error Occred in the application:";
message.Body = ex.Message;
SmtpClient client = new SmtpClient("smtp.gmail.com", 587);
client.EnableSsl = true;
client.Credentials = new NetworkCredential("user", "password");

Is there any other way we have without giving credentials to send the message?