Exchange 2003 68gb limit

Does someone have an idea on the right way to manage this error: Exchange store ‘First Storage Group\Mailbox Store (XXXMAIL)’: The logical size of this database (the logical size equals the physical size of the .edb file and the .stm file minus the logical free space in each) is 67 GB. This database size is approaching the size limit of 68 GB.

Thanks, Dan