这个问题怎么解决？？？

[lightkkk]

The server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay for [e-mail]
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Runtime.InteropServices.COMException: The server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay for [e-mail]

Source Error:


Line 61: mail.Body = from.Text.Trim();
Line 62: SmtpMail.SmtpServer = "127.0.0.1";
Line 63: SmtpMail.Send(mail);
Line 64: }
Line 65: }
63行
这个问题怎么解决？？？

[lightkkk]

？？？？？？

[jinhuabb]

wo