Exchage 5.5 Mailbox Resources problem

I have created some email accounts in Exchage 5.5 SP3 without creating NT account. After I deleted these accounts in Exch. Admin., they are gone in recipents list. But there still have an entry in Mailbox Resources and showing that some of them are occupling spaces. I have try using raw mode, but there are no option to remove them. There are only one Exchange Server in the network. Can anybody help? Thanks