There is so much sensitive data passing back and forth on the internet now, and there are people who will attempt to exploit this where they can.  Phishing is a method sometimes used to find out sensitive information such as bank details and login information.  Reputable companies never ask for such information through emails, so never respond to an email with any sensitive information such as your bank login, account details, Mothers maiden name.  If in doubt, ignore it, report it and delete it.