Is there a way to place all outgoing mail in the HELD queue to review and approve manually? My knowledge of POSTFIX is limited and I've been trying the check_recipient_access and smtpd_sender_restrictions =
check_recipient_access = regexp:/opt/zimbra/conf/hold_outgoing.regexp but I'm not able to get anything to work.

I'm assuming that adding anything to the /opt/zimbra/common/conf/main.cf file isn't the best approach since that file might be overwritten and my changes lost.

I read elsewhere on this forum about building a postfix transport file and adding it to Zimbra but I'm not sure this applies to what I'm wanting to do (the other post was wanting to block (not hold) to only a specific domain and I'd like to place out going mail in the held queue.

Thank you for anyone that has suggestions.