Visa will never send you an e-mail asking for confidential information such as account numbers, passwords, PIN numbers, credit card numbers or social security numbers.
Protect yourself from fraudulent e-mails (phishing attempt) claiming to be from a credit card company, bank or other popular Internet web site. Delete unsolicited e-mails that ask for this type of personal information. If you suspect you've provided confidential information to a fraudulent site, contact the customer service number on the back of your card or from your account statement.
You can report e-mail fraud claiming to be from Visa by attaching the suspicious message to an e-mail addressed to: phishing@visa.com