We have a zimbra server that we use for sending mails for all our applications. For this we added some trusted MTA networks:

zmprov getServer zimbra.capegroep.nl | grep zimbraMtaMyNetworks
However, even after rebooting the system we still get the following error.

Aug 29 15:59:53 zimbra postfix/smtpd[9686]: NOQUEUE: reject: RCPT from cqa.btc.echelon.nl[]: 554 5.7.1 <someone@otherdomain.nl>: Relay access denied; from=<no-reply@capegroep.nl> to=<someone@otherdomain.nl> proto=ESMTP helo=<esb.capegroep.nl>
In here esb.capegroep.nl is the server that sends the relay request to our mailserver and cqa.btc.echelon.nl is the public address of our network.

What are we missing to enable our relay request?