For each store, and event ID 1221 is logged after online defrage completes. In the text will be the amount of whitespace. THe 1221 you site is for the public folders. Are there any more? MS recommends that online maintenance, including online defrag, complete at least once every two weeks. If this is not happening,then you need to enlarge the window in your is maintenance schedule.
Once you delete an item from a mialbox, a pointer is marked deleted for the deleted items retention period. At the end of that period, if no pointers to an object exist, the object reference is remove and the space the object once occupied is marked as free space. This happens DURING ONLINE MAINTENANCE. If online maintenance never completes, nothing will ever be marked deleted, no pages will be freed, and your database will continue to grow.
The process is:
1. Delete items
2. Wait for DIR to expire
3. Wait for online maintenance
4. Wait for online defrag
5. Verify freespace in the event 1221
Then, if and only if you have a large amount of free space that will neve conceivably be reused, you may consider an offline defrag if all of the below are true:
1. You are running standard or SBS and have no ability to create another store in your environment.
2. You are short on space
3. The whitespace will never fill again.
At a 135GB store, I'd bet you're running Enterprise. First, make sure the online maintenance, including online defrag completes. Next, create a new DB. After that move all the user mailboxes to the nesw db. Lastly, dismount and delete the old db.