Web Hosting Talk : Web Hosting Main Forums : Dedicated Server : How to throttle mail bandwidth?

[BrianHawley]

Does throttling the bandwidth on an IP number have any effect on mail, or does it just throttle site access (and webmail)?

If not, what is the best way to throttle mail bandwidth? Any recommended third-party tools?

[BruceT]

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.

[BrianHawley]

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?

[BruceT]

Interesting scenario.

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...

[BrianHawley]

Yes, I guess inbound has to come through the IP as mail.mydomain.com hooks through it.

Outbound is not a major issue as most of our customers use MS Outlook (and the ISP's SMTP) for big attachments.

I'm also considering

http://www.snert.com/Software/mod_throttle/

Might try it out on a single Raq to see how it goes. Anybody here using it and can give a report?

I'll let you know how I get on.