I am trying to send an email with C# code, copied from examples on MSDN (e.g. https://msdn.microsoft.com/en-us/library/14k9fb7t%28v=vs.110%29.aspx)
// from and password contain my credentials
// to contains a valid email address
public static void CodeExample()
{
try
{
using (MailMessage mail = new MailMessage(from, to))
{
using (SmtpClient server = new SmtpClient("smtp.googlemail.com"))
{
mail.From = new MailAddress(from);
mail.To.Add(new MailAddress(to));
mail.Subject = "Test subject";
mail.Body = "Test message";
mail.IsBodyHtml = false;
server.Port = 465;
server.Credentials = new System.Net.NetworkCredential(from, password);
server.UseDefaultCredentials = true;
server.EnableSsl = true;
server.ServicePoint.MaxIdleTime = 1;
server.Timeout = 60000;
Console.WriteLine("Sending to {0} by using SMTP host {1} port {2}.", to.ToString(), server.Host, server.Port);
server.Send(mail);
Console.WriteLine("mail Sent");
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
Console.WriteLine("Inner Exception:");
Console.WriteLine(ex.InnerException?.ToString());
}
}
But I always get an exception:
System.Net.Mail.SmtpException: Failure sending mail. ---> System.IO.IOException: Unable to read data from the transport connection: net_io_connectionclosed.
The ‘from’ address details have been checked and seem OK. Sending from a Yahoo! account fails in the same way. I have tried lots of different combinations of SmtpClient properties. There are no messages in my firewall log.
Using Thunderbird, I can send from both the Googlemail and Yahoo! accounts without problems.
I would be grateful for any hints on how to get this to work.
Edit
I have seen this post SmtpException: Unable to read data from the transport connection: net_io_connectionclosed
Google mail fails on port 587 (both using and commenting-out UseDefaultCredentials = true and EnableSsl = true), reporting that I have an insecure app. I will try Yahoo! on port 587 later.
