Zimbra is a desktop mail client from yahoo. yahoo bought this two years back. With this mail client you can download yahoo mails for offline reading. This mail client also supports pop3 services to other mails also like Gmail and AOL.
you will have to enable the IMAP service of your Gmail in order to use this application
If you want to access the pop3 access for yahoo mail either you will have to buy yahoo mail plus or you will have to install third party software like YPOPs. So using Zimbra you can avoid that issue.
the download is nearly 49MB.
read more and download