Many administrators set a cap on the maximum size for a mailbox in Exchange, both version 5.5 and 2000. This is always a wise idea, since storage space on even the largest of servers is still finite and users will always find ways to fill any available storage. In one particularly egregious scenario I learned of firsthand, an organization with an Exchange server with no mailbox limits and an enormous amount of disk space soon nearly ground to a halt because people were using their Exchange mailboxes as file repositories. This is obviously a worst-case scenario, but the point is that the best way to stop this sort of thing from ever accruing is to set hard limits from the beginning.
Setting the maximum size of a mailbox in Exchange is not difficult. Launch the Exchange Administrator, go to the server you want to set mailbox limits on, expand it, right-click the Private Information Store object, and select Properties. Under the General tab, there are three entries in the Storage Limits section:
- Issue warning
- Prohibit send
- Prohibit send and receive
Each of these has a checkbox and a text box for defining a value in kilobytes. "Issue Warning," when checked, will issue warnings to users when their storage allocation goes beyond the value specified. When "Prohibit Send" is checked and a value specified, Exchange will forbid users from sending mail when their storage exceeds the listed value. "Prohibit Send and Receive" will do just that when it is selected and when storage for a given user is over the specified limit. When done, click OK. The exact values for these will, of course, depend on how much storage you have planned for and may be ratcheted up or down over time, conditions permitting.
As far as the physical limitations of the size of any given mailbox, the Standard edition of Exchange has a limit of 16 GB per mailbox. The Enterprise version, however, is only limited by the size of an NTFS volume (16 terabytes).
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.