error sending mail

Hi Everyone

why do some of my emails go through and some not. This is the error message i am getting after upgrading to 2.65

System.Net.Mail.SmtpException: Failure sending mail. ---> System.IO.IOException: Unable to read data from the transport connection: net_io_connectionclosed. at System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read, Boolean readLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller) at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint) at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint) at System.Net.Mail.SmtpClient.GetConnection() at System.Net.Mail.SmtpClient.Send(MailMessage message) --- End of inner exception stack trace --- at System.Net.Mail.SmtpClient.Send(MailMessage message) at Nop.Services.Messages.EmailSender.SendEmail(EmailAccount emailAccount, String subject, String body, MailAddress from, MailAddress to, IEnumerable`1 bcc, IEnumerable`1 cc) at Nop.Services.Messages.EmailSender.SendEmail(EmailAccount emailAccount, String subject, String body, String fromAddress, String fromName, String toAddress, String toName, IEnumerable`1 bcc, IEnumerable`1 cc) at Nop.Services.Messages.QueuedMessagesSendTask.Execute()

hope someone can help

Did you make any changes on your IIS server?
You may want to Google  "System.IO.IOException: Unable to read data from the transport connection"
e.g. http://forums.asp.net/t/924682.aspx

sorry new york should have edited this one. been having a bit of trouble with nopcommerce for the last couple of weeks. and very busy in my business at the moment.

it was because i didnt delete the other fictious email accounts in nopcommerce. As soon as i did that then everything worked fine.