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("frommail@mail.com", 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.