Exchange2000 remove a domain mail acct

I had 2 domains assigned to my Exchange 2000 server (example: dom.ch and dom.com). Both were routed throgh my service provider’s DNS server. I received mail ok for both domains. Later, I stopped hosting dom.com and the service provider removed it from their DNS server. I elimated all traces of the dom.com mail boxes and users from my exchange server, but I cannot send mail to the dom.com domain which is now being hosted by another provider. (Outgoing mail is being trapped within my dom.ch domain and stays on my exchange server. Ping of mail.dom.com correctly returns the IP address of the dom.com mail server which is hosted elsewhere. What else needs to be removed on my echange server to stop trapping the outgoing mail to acconts on dom.com? Thanks Y’all