Unable to connect to remote server

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I created a page to send email through my company's SMTP email server. It worked well before. But I got Exception: "Unable to connect to remote server, An attempt was made to access a socket in a way forbidden by its access permissions" even though I did not change anything on the code. How can this problem get fixed? Thanks in advance.

Posted 15-Apr-14 1:11am

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hypermellow · Answer 1 · 2014-04-15T01:22:00

Solution 1

The issue appears to be a change made to your company's SMTP server.

Without seeing your code, it's difficult to guess.
Maybe the SMTP server previously allowed unauthenticated connections and now it doesn't?

Posted 15-Apr-14 1:22am

hypermellow

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[no name] 15-Apr-14 9:08am

Checked w/ SMTP Server admin and was told no change on his side. My code is below. Thanks.
SmtpClient Smtp_Server = new SmtpClient();
MailMessage e_mail = new MailMessage();
Smtp_Server.UseDefaultCredentials = false; // true or false - no effect
Smtp_Server.Credentials = new System.Net.NetworkCredential();
Smtp_Server.Port = 25;
//Smtp_Server.EnableSsl = true;
Smtp_Server.Host = "mailhost.myCompany.com";
Smtp_Server.UseDefaultCredentials = false;
e_mail.From = new MailAddress(txtFrom.Text);
e_mail.To.Add(txtTo.Text);
e_mail.Subject = txtSubject.Text;
e_mail.Body = txtMessage.Text;
e_mail.IsBodyHtml = false;
Smtp_Server.Send(e_mail); // Error: Send email failed

hypermellow 15-Apr-14 9:30am

Your code shows you are trying to send an unauthenticated email via SMTP.

If I try the same, using an SMTP server that does not allow unauthenticated relaying of messages I received the following exception:

System.Net.Mail.SmtpException: Failure sending mail. ---> System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: An attempt was made to access a socket in a way forbidden by its access permissions xxx.xxx.xxx.xxx:25\r\n at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)\r\n at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Exception& exception)\r\n --- End of inner exception stack trace ---\r\n at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6)\r\n at System.Net.PooledStream.Activate(Object owningObject, Boolean async, GeneralAsyncDelegate asyncCallback)\r\n at System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback)\r\n at System.Net.
ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout)\r\n at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)\r\n at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)\r\n at System.Net.Mail.SmtpClient.GetConnection()\r\n at System.Net.Mail.SmtpClient.Send(MailMessage message)\r\n --- End of inner exception stack trace ---\r\n at System.Net.Mail.SmtpClient.Send(MailMessage message)\r\n at xxxx.xxxx.xxxx.myMethod(String sFirstName, String sSurname, String sEmailAddress, String sPendingAssessment) in \\\\<server>\\<path to website>\\App_Code\\<my class="">.cs:line xxx

You can compare this exception to you own.

What happens when you remove the line:
Smtp_Server.Credentials = new System.Net.NetworkCredential();

If your code previously worked, and your running it from the same location, it looks like there has been a change to your SMTP server config.

[no name] 16-Apr-14 7:13am

To: hypermellow: I agree your point: my SMTP server config may have some changes. I will check with our SMTP server's admin. Thanks.