[Typo3] Direct Mail error

[Henrik Eriksson]

I'm using the Direct mail plugin and recieve this error when trying to send 
a testmail. Any suggestions what to do?

*Warning*: mail()
[function.mail<http://localhost/henrik/typo3/ext/plugin_mgm/modules/function.mail>]:
SMTP server response: 550 RCPT TO:<typo3henrik at gmail.com> Relaying not 
allowed - please use SMTP AUTH in *
c:\Inetpub\wwwroot\testsite\typo3\t3lib\class.t3lib_htmlmail.php* on line *
652

/*/Henrik*
*