Exchange 2007 does not receive emails

Hi,
I set a new Exchange 2007 Server.Everything seems to be fine BUT :
1. May send and receive emails within domain
2. May send emails out to internet
3. Can not receive emails from internet.

All DNS records are correct. MX record is correct.
May telnet port 25 from internet. Once I sent email from internet to my email server –> error :
You do not have permission to send to this recipient. For assistance, contact your system administrator.SMPT connector is configured.
Any idea , what is possible wrong ?
Thanks in advance