C# – SMTPException : Unable to read data from the transport connection: net_io_connectionclosed

cemail

I know that this question looks like duplicate of dozens other questions while its not.

When ever i try to send an email on my local machine through my web application an SMTPException is thrown and the exceptions is :

//on this line : SmtpServer.Send(mail);
Unable to read data from the transport connection: net_io_connectionclosed.

While the code on production is working perfectly, the same code, the same connections, the same credentials, i'm using IP instead of alias, i tried to turn off the firewall on my local machine, and nothing helped me to fix this issue.

While on my local machine is used to work previously, can anyone give just a hint what could be the problem that raising this issue?

Best Answer

If you are on a residential internet connection, quite often your ISP will block outgoing email sends by blocking all outbound connections to port 25. This is quite common here in the US. Try connecting to a local email server over TCP/IP, or to one on your own internal network.

Related Solutions

C# – How to update the GUI from another thread

The simplest way is an anonymous method passed into Label.Invoke:

// Running on the worker thread
string newText = "abc";
form.Label.Invoke((MethodInvoker)delegate {
    // Running on the UI thread
    form.Label.Text = newText;
});
// Back on the worker thread

Notice that Invoke blocks execution until it completes--this is synchronous code. The question doesn't ask about asynchronous code, but there is lots of content on Stack Overflow about writing asynchronous code when you want to learn about it.

Jenkins – How to set the Sender’s address in Jenkins

Jenkins uses the System Admin e-mail address as the sender address for e-mail notification. You can configure this under Manage Jenkins -> Configure System. This is under the Jenkins Location header on that page! It is not immediately obvious that this setting is tied to the e-mail notification settings, since it is not under the E-mail notification header on the configuration page.

Best Answer

Related Solutions

C# – How to update the GUI from another thread

Jenkins – How to set the Sender’s address in Jenkins

Related Topic