Did you know you could check your Gmail and Hotmail accounts right from Yahoo! Mail? With external accounts feature in Yahoo! Mail you can pull your emails from any service that supports POP protocol into Yahoo! over SSL. To set this up, go into Mail Options and click on "Accounts". Then click "Add Account" and specify the POP server for the respective service. If the email provider only supports SSL connections make sure to change the port number to 995.
See the screenshots below: