I am running Exchange 2003EE on Server 2003EE over here. On a weekly basis I maintain about 10 mailboxes that usually grow upwards of 10gigs a week. I only leave 1 week worth of mail in the box at any given time. So when I do the Full backup (Mailboxes and IS) I see the size reflected in the size of the Mailbox backups yet the Information Store continues to grow. I purge all mail from the inbox, deleted items and from recover deleted items. Aside from an offline defrag is there something else I am missing?