[求助]发外邮件时提示错误。求解?

yuyi8228

The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'edp@datafield.com.hk'. Subject 'dd', Account: '192.168.168.56', Server: '192.168.168.56', Protocol: SMTP, Server Response: '550 5.7.1 Unable to relay for edp@datafield.com.hk', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79<br>
Exchange服务器邮址：administrator@serverdatafield-cn.com

钉子

1.是否选择了，身份验证？<br>
<a target=_blank href=http://5dmail.net/bbs/Announce/announce.asp?BoardID=35&ID=7413&r=7650&Upflag=0&p=0&q=1>http://5dmail.net/bbs/Announce/announce.asp?BoardID=35&ID=7413&r=7650&Upflag=0&p=0&q=1</a><br>
2.是否有防火墙？<br>
<a target=_blank href=http://5dmail.net/bbs/Announce/Announce.asp?BoardID=11&ID=4953>http://5dmail.net/bbs/Announce/Announce.asp?BoardID=11&ID=4953</a>