关于smtp的问题，真的可以解决哦！我就是这样成功的！

这两天做了一个小PROJECT，大致是一个SERVER监控系统，如果发现某部SERVER有异常，发送EMAIL到相关手机，以便在非工作时间和节假日也能及时知道系统故障。
其中一个功能就是发送EMAIL。程序是这样的：
myMailMsg.To = "888888888@mobile.att.net";
myMailMsg.From = "support@medicalit.net";
myMailMsg.Subject = "server down";
myMailMsg.Body = "Please call StarLan to chen Database Server";
myMailMsg.BodyFormat = MailFormat.Text;
SmtpMail.SmtpServer="localhost";
SmtpMail.Send(myMailMsg);
本来是用外部的SMTP SERVER
 SmtpMail.SmtpServer="smtp.XXX.com";
但后来发现由于DATA CENTER的FIREWALL原因，改用
 SmtpMail.SmtpServer="localhost";
运行后系统提示错误信息：
Email Fail
Could not access 'CDO.Message' object.
Here is the full error message output:
System.Web.HttpException: Could not access 'CDO.Message' object. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Runtime.InteropServices.COMException (0x8004020F): The server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay for 12321323@mobile.att.net
检查SMTP SERVICE，正常，估计是权限设置问题。打开IIS ADMIN，右键点击SMTP VIRTUAL SERVER，选择属性，在ACCESS中点RELAY，增加127.0.0.1。一路OK回去。
这时候再运行程序，邮件发送成功。