The bandwidth limiting on a Cobalt is a moment-by-moment throttle of all TCP/IP throughput for a given IP address in kilobits per second. There is no way to specify only mail, only web, etc. It just clamps everything, including the admin interface.
It also does not measure bandwidth over time - i.e., 10MB per month, and once 10MB has been transferred, all further traffic is cut off until the next month. Stricly sets the pipe size and that's it.
Yes, I understand that. I'm just a bit unclear about how the POP3 and SMTP is delivered.
As there is a single mail-server, does POP3 and SMTP for (say) mail.mydomain.com (on its own IP address) get throttled according to that IP address's kbps setting, or not?
I am presuming it does, just want to be sure.
The problem: A couple of customers are hammering the system with vast mail transfers (big attachments, not spam). Transfer voloume is not an issue, but bandwidth is. Will putting them on separate IPs and throttling them solve the problem, or do I need a third-party software solution?
I _think_ what you are proposing should work, but primarily on the inbound side. Outbound, all mail comes from the "main" IP on the server the way sendmail is set up by default... there _is_ a "genericstable" feature you can include in the cobalt.mc file (used to build sendmail.cf) that "virtualizes" outbound mail... I've never really messed with it, though, so I don't have any procedures or "gotchas" for you if you want to try it.
Let me know how you make out - would make an interesting "how to" for the archives...