Not sure if this is the right place to ask this question, but I'm stumped on this as I'm developing this control panel. I'm monitoring traffic flow via the switch for IP based hosting accounts, but named based hosting is an issue. I can utilize some Apache modules to monitor traffic to a website, but cannot figure how I'd do it with FTP and Sendmail? Any ideas or resources I could follow up on?

hmmm... did you check out your ftp software log file? Sendmail can be a problem but I am sure someone has traffic management module/script out there.. did you check out sourceforge.net and freshmeat.net projects?

ps. you can also write a script that will pull out all file size from the access logs and sum it up