How can I configure zimbra to receive mail only from spam filter gateway

[clearlogic]

Hi
I'm using Zimbra open source edition 5.0.18 on Red Hat Enterprise Linux 5.
I have a spam filtering gateway that filters all the e-mails coming to my domain and relays the filtered e-mails to Zimbra.
However, there are some spams sent directly to Zimbra to avoid spam filtering.
Since I disabled Zimbra anti-spam service, I cannot stop spams sent directly to Zimbra.
How can I configure my Zimbra to receive e-mails only from the spam filtering gateway and authorized SMTP users (that send e-mail using Outlook).
Both spam filtering gateway and zimbra have a different public IP address.
Any advise would be appreciated.

Thank you in advance.

[phoenix]

Originally Posted by clearlogic

However, there are some spams sent directly to Zimbra to avoid spam filtering.
Since I disabled Zimbra anti-spam service, I cannot stop spams sent directly to Zimbra.
How can I configure my Zimbra to receive e-mails only from the spam filtering gateway and authorized SMTP users (that send e-mail using Outlook).
Both spam filtering gateway and zimbra have a different public IP address.
Any advise would be appreciated.

If the Zimbra server has Port 25 open on it's public IP then just block it at your firewall and you'll receive no email to that server. If you don't want external email sent into Zimbra why is it on a piblic IP rather than on a NAT LAN IP?