Exch 5.5 , Demand Dial Router , Queuing

Hi ,

Our set up is and exchange 5.5 server SP4 , a Zyxel ISDN Router which dials on demand for web access and for E-Mail (SMTP) . The problem is that we only want to send E-Mail every hour . Currently when an E-Mail is sent from a client , it goes to the Exch Server and then to the router which triggers a dial up. This was fine until people started using E-Mail more frequently and now the router is up for most of the day . I'm looking for a way to hold the mail in Exchange for an hour and let it build up until the scheduled time. I know this is easy if you are using a modem , but the 'every hour' options are greyed when not using a dial up connection to retrieve mail.

Any help ?

Thanks