Shivakumar,
Some thoughts:
I wanted to make sure you knew that you didn't have to change the SMTP Server name just to send e-mail to a Yahoo e-mail address. You can stick with your corporate SMTP server and send e-mail to any valid address, assuming your company firewall isn't configured to block e-mail to addresses outside the company.
If you changed the SMTP server name because you are now trying to send the e-mail from somewhere that doesn't have access to your corporate SMTP server, then there are several issues. First, any public SMTP server that doesn't require user authentication will instead do something else (like look at your IP address) to determine whether or not it will allow you to send the e-mail. Otherwise, spammers would saturate the server with SMTP requests for as long as it remained available.
Assuming you're trying to use a server that will allow you to use it, are you sure you got the right server name? You should double-check that.
Finally, it may be that your SMTP server requires user authentication. Yahoo's public ones certainly do; see the
Yahoo Help Page on this (http://help.yahoo.com/help/us/mail/pop/pop-11.html). If this is the case, you may be able to use some alternative VIs created by Rolf Kalbermatter to get the job done, though you should be aware that it could be dangerous to do so. See
this thread.
Regards,
John