Sorry I should have added:

This is the error:

There has been an error trying to send the test email. The error is:
There is a problem with the configuration of your SMTP Server. Mail was not sent.

This is the Log File

2013-07-03 10:00:14,648 [BLUESTAR][Thread:58][ERROR] DotNetNuke.Services.Exceptions.Exceptions - 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 DotNetNuke.Services.Mail.Mail.SendMailInternal(MailMessage mailMessage, String subject, String body, MailPriority priority, MailFormat bodyFormat, Encoding bodyEncoding, IEnumerable`1 attachments, String smtpServer, String smtpAuthentication, String smtpUsername, String smtpPassword, Boolean smtpEnableSSL)