Unless you are a small company with only one mail server, DAOS by itself will not solve your disk problems because it only consolidates one server at a time not across servers.

The way to fix it is to consolidate your old mail to an archive server and implement DAOS on that server.  You will get much better disk savings because all the duplicate mail is now on the same server.

Use ReduceMail Pro Archive to consolidate the old mail to a single archive server!