According to the page below, you can set up an email client for your mail access. Hope this helps.
http://help.yahoo.com/us/rogers/tutorials/cg/cg_access4.htmlAfter you get the client set up, let it download your inbox. THEN create a folder for temporary use, move the inbox contents to the folder.
Next create folders with the same names as your web based mail folders.
Move the messages from one folder to the inbox, open up the email client, download, then move them to the newly created folder. Repeat this process for each folder.
Finally, move the contents of the Temp folder back to the inbox.
If you have any questions about the client you set up, all you have to do is ask, and someone will answer them.