I installed Zimbra 5.0.11 on a fresh Ubuntu 8.04 with the domain example.com

Cause not all Mailbox are stored on Zimbra, i want to send all mails first to the extern smtp server from the provider. for this i used following commands:
zmprov md example.com zimbraMailCatchAllAddress @example.com
zmprov md example.com zimbraMailCatchAllForwardingAddress @example.com
zmprov md example.com zimbraMailTransport smtp:smtp.provider.com
after sending a mail to test@example.com, the mail still pass the local smtp server and not the smtp from the provider.
when i look in the mail.log, i see
to=test@example.com, relay=zimbra.example.lan[LAN-IP]:7025
but with the above commands this mail should be sent to smtp.provider.com.

Any help?