Email today is important and can be personally. To protect your email you should change your email password at least every 3 months.
You can change your password at Webmail (http://webmail.rpxholding.com) Choose menu Options >> Account Administration, enter your password for confirmation then you can type your new password in Passwords field
To reset DNS cache on Windows:
Open Command Prompt (Click Start >> Run type command) then hit Enter button
then type "ipconfig /flushdns"
This will clear your's PC DNS cache or if you are using Windows XP open Control Panel, Network Connections then right-click choose Repair button