I just switch over my mail server to Zimbra mail server...

But I encounter some problem , certain email cannot send out by Zimbra. But the previous mail server can send out email using the same address.

This is the bug error:

javax.mail.SendFailedException: Invalid Addresses; nested exception is: class com.sun.mail.smtp.SMTPAddressFailedException: 554 5.7.1 <cyooklan@yahoo.com.cn>: Relay access denied at com.sun.mail.smtp.SMTPTransport.rcptTo(SMTPTranspo rt.java:1141)
May I know what the problem mean and how can I fixed the problem?

Thank you