How to delay user not found messages

Hello,

I need to delay exchange 2013 messages that can't find the user.  We are a 2013/10  hybrid with 365.  It takes time for our identity management system to create an AD account and then DirSync it to 365 and then create the mailbox.  But we want messages to those 'almost valid' email addresses to be queued during the time the mailbox is being provisioned.

Is there any way to do this?

Thanks,

Peter