asp.net NetworkInformationException on sending mail - what can be the reason?

SmtpClient smtp = new SmtpClient(smtpServer);
smtp.Send(msgMail);

On second line sometimes this exception is thrown:

System.Net.NetworkInformation.NetworkInformationException:

with Message: "A non-blocking socket operation could not be completed immediately"

What does that mean? What can be the reason?

Mail sending in general is working most times. It's a IIS7 Windows 2008 Server machine.

Thank you.

Edit:

I found something here: http://www.thevbzone.com/modWINSOCK.bas

Public Const WSAEWOULDBLOCK = (WSABASEERR + 35)      ' A non-blocking socket operation cou开发者_JAVA技巧ld not be completed immediately

MSDN says about this error (http://msdn.microsoft.com/en-us/library/ms740668%28VS.85%29.aspx):

Resource temporarily unavailable.

This error is returned from operations on nonblocking sockets that

cannot be completed immediately,...

So, what does that mean actually? Should I just ignore the error, resend the mail...? thanks.

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First of all you should check ErrorCode property of NetworkInformationException and then find this error code in this ms article. It gives to you more information about exception.