Exchange mailbox database files (EDB-files) grow in size as the data within them grows. But when data is removed, their file sizes will not shrink back. Instead, the file will contain "white space", which will be re-used if additional space is needed again.

Older versions of Exchange (2007 and earlier) did (limited) automatic space reclamation as part of their online database maintenance routines. Starting from Exchange 2010, these maintenance routines have changed and space reclamation no longer occurs. It is up to the Exchange administrator to perform space reclamation if the need arises.

There are two viable methods for reclaiming disk space, each having their pros and cons:

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