Running a Debian Sarge "perfect" setup with ISPConfig, all seems to be going pretty smoothly, but the statistics seem very odd. There are about 70 domains being served, most of which use mail forwarding, some have mailboxes on the server, and a few use external mail servers. The ones with external mail servers show hundrds of megabytes of mail traffic, despite having the MX records pointing to a different address - there should be almost none recorded. The ones with mailboxes on the server seem to give about the right figures (guessing at the likely traffic). The ones with mail forwarding mostly show little or no mail traffic at all. This is running Courier for the mail. I'm baffled by this! Can anyone suggest what may be wrong, or how to fix it?