Regular Maintenance Tasks for Exchange

Back up the information store and directory (ideally, a full backup)
Check backup log to ensure that system backups worked
Check event log for any error messages relating to Exchange services
Check size of information store and amount of space available on the disks where the stores (and directory store) are located
Check the queues for all connectors and take action to discover the cause if you find more than 50 messages in a queue
Check the available disk space on the disk where the MTA work directory is located
Take whatever actions are required to collect statistics from the system
Review the space users occupy in the information store, and pay special attention to users who are approaching their quota