I can understand the EDB being larger than what ESM would report the mail store size as since the EDB doesn't shrink unless you do an offline defrag. I can't understand how ESM is reporting the entire server's mail stores at 417GB but all EDBs and ESMs combined equal only 314GB. I'm stumped. Any ideas? I'm worried this server is having problems and this is the only clue so far. Thanks

Where is ESM reporting this? Or are you adding up all of the mailbox sizes and getting 417GB. Then you are probably seeing some benefits from "single instance store" or SIS. This means that a message is only stored one time per database even if there are 100 receipients (whose mailboxes on that datatabase).

Thanks for the quick reply. Navigated in ESM to: Admin Groups>Servers>Server>Storge Group>Mail Store>Mailboxes and then exported the list. I guess single instance storage makes sense. I've just never seen it so effective. Thanks for the insight!