'Transaction failed. The server response was: 5.7.1 Relay access denied in asp.net'

[EDN Admin]

<font size=2><font color="#008000" size=2><font color="#008000" size=2><font size=2><font size=2>
I am getting the following exception when ever i send mails to external mail-ids such as mailto:xyz@yahoo.com xyz@yahoo.com .

Transaction failed. The server response was: 5.7.1  Relay access denied in asp.net

i have googled , search in msdn forums but no use.
i have tried all the possibilities but all went in vain.

i added below statement also.
smtpclient.Credentials = </font><font color="#0000ff" size=2><font color="#0000ff" size=2>new</font></font><font size=2> System.Net.</font><font color="#008080" size=2><font color="#008080" size=2>NetworkCredential</font></font><font size=2>(</font><font color="#800000" size=2><font color="#800000" size=2>"username"</font></font><font size=2>, </font><font color="#800000" size=2><font color="#800000" size=2>"password"</font></font><font size=2>);
<font color="#008000" size=2><font color="#008000" size=2>tried smtpclient.UseDefaultCredentials = false; and also with true.
</font></font>
in my windows live mail email client application
we have enabled My server requires authentication under Server> Outgoing Mail Server tab so that mails can be sent to external mail ids.
</font></font></font></font></font><font size=2>
do we have to set settings like this? </font>

View the full article