Workflow Manager's Mailbox functionality allows the user to capture the conversation happening out of the system in form of mails, to be recorded in the Asite Workspace system. Users can send email directly to a folder within a Workspace.
This functionality also allows the users to Publish documents to a folder within a Workspace by just attaching documents and mailing them.
Useful Links:
Change Workspace Mailbox Configuration
Send Email to a Workspace Mailbox