I've got a company behind a Netscreen 5 firewall but the users access an Exchange 5.5 server (NT for now) outside of the firewall.
Everthing works fine except that the new mail notifications from the server are being blocked by the firewall. Checking into it I found out that Exchange uses random udp ports to send these notifications. I've tried a policy on the firewall to allow all services from the Exchange server itself to get through. I also created a custom server and set it to let in all udp ports from the Exchange server i.p. address but it still doesn't work.