With Shared Folders you can easily grant specific access to your e-mail folders to your co-workers. You can decide which user can view which folder and if they can only view it or also modify it.

The folders shared by others with you will be available under a special folder called 'shared' in your IMAP folders list.

 

Since the Shared Folders is an IMAP level feature, this functionality is available in both your e-mail client and Webmail, wherever you are.