Sending Email from web page-send.objmm error

[Mitendrasinh]

when icomile the code th folowing error come .I have downloaded the
code
from
http://www.4guysfromrolla.com/webtech/080801-1.shtml .and run it but
it give
me followin error .
******************************************************
The "SendUsing" configuration value is invalid.
Description: An unhandled exception occurred during the execution of
the
current web request. Please review the stack trace for more
information
about the error and where it originated in the code.

Exception Details: System.Runtime.InteropServices.COMException: The
"SendUsing" configuration value is invalid.

Source Error:

Line 41:
Line 42: 'Now, to send the message, use the Send method of the
SmtpMail
class
Line 43: SmtpMail.send (objMM)
Line 44:
Line 45:

Source File: c:\inetpub\wwwroot\sendmailthink\WebForm1.aspx Line: 43