Mail routing after error

We have had an issue with the router on our server crashing, resulting in large numbers of emails sitting in the mail.box’s. When the router is restarted, only the recent emails are delivered immediately. the rest get delivered at some random time later. I remember reading something about delayed emails try to be delivered, if delivery fails the router waits a bit of time then re-tries. If it fails again, the router waits a bit longer. restarting the router does not fix this issue. Is there anyway to get the emails that have been waiting greater than 2 hours to route? I know that if I just wait , they will all be delivered.