The Yahoo Zimbra Desktop interface looks a lot like the Yahoo Mail web interface, so users should have no trouble picking up the new software. Setting up your Yahoo Mail account is easy. Just enter your username and password and it does the rest. You can select how often Zimbra looks for new mail ranging from every 5 minutes to every couple of hours. Zimbra uses the IMAP protocol for communication with your Yahoo Mail account which means that whatever you do on your desktop software gets reflected on your main web based Yahoo account as well, so you don't have to worry about deleting a bunch of messages only to see them when you log back in.
In a nod to the reality of users with multiple email accounts, Zimbra allows you to setup and connect to multiple accounts including Google email accounts. Again, the settings come pre-installed with the program so adding a Google Email account is just as easy as adding a Yahoo email account. Gmail supports IMAP as well, so you can manage your Gmail account from the Zimbra interface. Switching between email accounts is a snap, and when you send an email, it sends from the account you have open so you don't have to worry about accidentally replying from the wrong email account.
Zimbra also integrates with Calendars, Tasks, and Contacts (Yahoo and Gmail) with the same interface making this heaven sent for those home office users who end up with Contacts and Tasks across both email systems.
Most importantly, it is all so very easy. The accounts are set it and forget it, and I didn't have to go through the trouble of entering in server names and port numbers for the Yahoo and Gmail accounts which are ready to go from the start. My hosted accounts, of course, took a bit more setup but no more than any other program, and much easier than most.
As an added bonus, Zimbra runs on Macs and Unix too, so if you are a home office user with not just multiple email accounts, but multiple operating systems as well, you are in business.