More then half of the space used on our shared host account is related to email accounts. I need to down size this number to a LOT less.
We must configure our client email application to "NOT leave a copy on the server".
Let's suppose our system has downloaded the message but that the message is still marked as new: if we configure our email accounts using IMAP, will that message be available on another machine, since the email has not been read?
If you don't want mail left on the server, then IMAP is not the protocol you should be using. The whole idea with IMAP is that the mail client talks to and views mail that is stored on the server so that all connecting mail programs see the same mail.
If you want your users to pickup there mail and then leave with it, you should be making them use POP. You can configure clients to look at messages and leave a copy on the server if they are left unread, but the prevailing model will be to download them then remove the remote copy.
Bonus suggestion: Buy an extra hard drive and offer your users IMAP service with extra space. Their lives will be better for it. Also you can put a per-user quota on the file system space so that you don't end up with a few people abusing the system.
