Mount mailbox after removing

Hi,

I have Exchange 2010 + Office 2010/2013. I removed mailbox for test user (just exchange mailbox, not AD account), deleted Disconnected mailbox from database and tried to assign new mailbox to the existing users. All operation went fine, but user status in Outlook is Disconnected.
Before deleting mailbox user used OST file.

Question: I want to delete user mailbox, clean database, create new mailbox for existing user and don't interupt end-user (using autodiscover using Outlook). Is it possible? What did I wrong? What should I do better?

Thnx.