I had a traffic explosion the last 4 year. I found the reason. The Outlook IMAP account did rise that traffic. Outlook is checking ALL mails stored on the webserver, which in this case is 45T mails to check. Outlook is doing that in the background and consumes 60-80 MB/hour. I converted the account to a POP account which consumes 0,8MB/hour. Quite a difference :-) Cheers Chris