Here are the settings that worked for me. As I mentioned I needed to try a few combinations, but these finally worked...
Send Setup
Server:smtp.mail.yahoo.com
Port: 25
Email:
you@yahoo.com
Nick: Your Name
Authentication: On
Same As Receive: Yes
Use SSL: No (This is important)
Receive Setup
Server

op.mail.yahoo.com
Port:995
User Name: user (only first part of email address, do not include your @yahoo.com prefix)
Password: Your Password
Re-Enter Password: Your Password
Keep On Server: Selected (Deselect if you want to delete mail off Yahoo)
Incoming Message Size:Your preference (I have 64k set)
Use SSL:Yes (This is important and different to the send options)
Signature Setup: Set this if you wish
Connection Setup: Make sure that you select a working Internet profile. Test your profile in the Browser before assuming it works.
If you follow the settings above you should have no problems accessing Yahoo from the E6.
Regards,
JamesK