Inbox.dtBase2 too huge??

I think something is wrong with my Inbox.dtBase2 file. My global Inbox when viewed in DTPro 2.0.2 is empty. My entire database is only 1.2GB.

But my Inbox.dtBase2 file ([username]>Library>Application Support>DevonThink Pro 2>Inbox) is 20.66GB!

What can I do to fix it? How do I keep it from happening again?

The Inbox package might contain backups and/or is not optimized. Apply Tools > Backup & Optimize multiple times and check the size again. Run Tools > Verify & Repair to check if there are orphaned files.