Deferred message to Inbox

Hi there,

I am a bit new to Zimbra but got a task from Management for tender purpose. What is really needed is when an email arrives on the Zimbra server, it must be delivered on a specific date (and time) on the receiver email account. The reason is for the concern of obtaining bids from suppliers. A closing date will be set for the bid and before that time, no one should be able to see the emails from the suppliers. We can put a specific subject name for this filtering.
I have look into the filtering method but it is not achievable. Can someone help?

Thanks

Heemal...