In your organization, everyone wants a large mailbox quota, as it would allow them to keep every email without deleting anything. There are ways to keep all of your data while keeping your mailbox size reasonable.
First, lets explain why keeping your mailbox size down is important: Smaller is better? Everything that you have (i.e. emails, contacts, calendars, tasks, etc) on your Outlook or Entourage client is actually mirrored on the Exchange server. One of the benefits of Exchange is that if you lose your laptop or your hard drive crashes, simply install your new Outlook client on your new computer and everything on the Exchange server will be pushed back to your new client.
Therein lies the problem - if your mailbox is too big, it could take a long time to send that data back to you (depending on your connection speed). Also, the larger your mailbox, the more prone to data corruption (which is impossible to avoid) you are. Keeping your mailbox size small also shrinks the target size for potential problems.
How to enforce your mailbox size policy?
Starting with large mailboxes is a simple choice, but getting everyone to trim down becomes more difficult. The best way to enforce your mailbox quota policy is to start with a smaller mailbox size and set up archiving rules (explained below). Also, it is recommended that there is a network file server to store all archived data files for employees to review at any time. For example - John Doe has archived everything older than 3 months to JohnDoe_2005.pst on the file server that ONLY John Doe can reach. This allows all things older than 3 months to be accessible through your network.
Archiving old data is a very simple process and can be done a couple of ways. Manually or Automatically. Please read best practices to better understand Outlook PST files. Either way, you must create a file to send the data to. In Outlook - go to File > New > Outlook Data File > click OK on the default type > Choose the name and location of the file. Once you have the file and location for your archived data, it is time to archive!
Manual Archive: The easiest way to save old data is to drag it from your existing Personal Folder to the folder on your Exchange server. Yes...it is that simple.
Automatic Archive: Setting up automated archiving is very easy in Outlook. There are also various methods of automated archiving (for more assistance see Help in your Outlook client).
For now, lets start at the most basic level which is archiving anything older than a certain date. In Outlook, click on File > Archive Select the Mailbox - username at the top of the list Make sure to select "Archive this folder and all sub folders" at the top. Next to "Archive items older than:" select a date for all email older than to be archived to you local PST file. Choose the archive folder location. It is advised to have these files on a networked file server or on the local hard drive that is backed up to the networked file server.