Here is a summary of the new Exchange 2010 archiving/retention features:
What is Personal Archive?
•A secondary mailbox that is configured by the administrator
•Appears alongside a user’s primary mailbox in Outlook or Outlook Web Access.
•PSTs can be dragged and dropped to the Personal Archive
•Mail in primary mailbox can be moved automatically using Retention Policies
•Archive quota can be set separately from primary mailbox
Can I have my personal archive on a secondary server?
For the best performance (search, retrieve, copy, etc), it was determined it would be best to be on the same server.
What is the user experience in a personal archive?
Can I search both my local mailbox and personal archive at once?
Yes, you can both search all subfolders or advanced search.
What are retention policies?
Retention policies in Exchange 2010 are the ability to expire emails either in folders or at the item level.
Are there e-discovery tools available now?
Yes, with Role Based Access Control (RBAC) and this new tool you can perform a legal search across mailboxes if needed and delegate this role to compliance officers, legal, etc.
Can I search archives and current mailboxes?
Yes and you can also search different content types.