System.Net.Mail.SmtpException: Service not available, closing transmission channel. The server response was: 4.4.2

Question

I get this error when I'm frequently sending some e-mail to a list of users. Say it sends 10 mails and 1 gives an error, then sends a couple more mails and gives the same error.

The code looks like this:

public static bool SendEmail(string toMail, string fromname, string from, string subject, string body, string BCC)
    {

        MailMessage mailmessage = new MailMessage("[email protected]", toMail, subject, body);
        mailmessage.IsBodyHtml = true;
        mailmessage.BodyEncoding = Encoding.GetEncoding(1254);
        mailmessage.SubjectEncoding = Encoding.GetEncoding(1254);

        SmtpClient objCompose = new SmtpClient("xxxx");

        try
        {
            objCompose.Send(mailmessage); 

            return true;
        }
        catch (Exception ex) { 

        }

        return false;
    }

And the error I get is this:

System.Net.Mail.SmtpException: Service not available, closing transmission channel. The server response was: 4.4.2 mailer.mailer.com Error: timeout exceeded at System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response) at System.Net.Mail.MailCommand.Send(SmtpConnection conn, Byte[] command, String from) at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException& exception) at System.Net.Mail.SmtpClient.Send(MailMessage message)

can anyone please help, this bug is killing me.

Thanks in advance.

Answer 1

Disposing the smtpclient (objCompose) did the trick.

    // Summary:
    //     Sends a QUIT message to the SMTP server, gracefully ends the TCP connection,
    //     and releases all resources used by the current instance of the System.Net.Mail.SmtpClient
    //     class.
    public void Dispose();