Vigilance is being urged after bogus emails containing viruses have been sent out, claiming to be from various authorities.
West Yorkshire Police said that one of the emails from someone pretending to be force is a fake invoice to the victim for £2,259.20 asking the recipient it to click on a link - which would download a Trojan virus to the their computer.
The force's Cyber Crime Team is now urging residents to be on guard following instances of 'phising'.
Another email circulating claimed to be from the West Yorkshire Police Camera Unit asking for details of the recipients' vehicle.
Detective Inspector Benn Kemp said: "West Yorkshire Police are aware of a number of methods that criminals attempt to gain access to your system or steal from you.
"Please ensure that if you do receive an email that you are not expecting, get a bill you know nothing about or receive any form of link or document that you feel may be bogus, please don’t click on the link, delete the email immediately and report the email."
"Some fraudsters claim to be from West Yorkshire Police or other bodies such as the HMIC or the NHS to trick you. Always be on guard and never click on a link / open an email that you’re not expecting."
West Yorkshire Police said that it would never correspond via email requesting personal information and would encourage anyone who receives an obviously fraudulent email to delete it and not to click on any links.
Report the emails to Action Fraud at http://www.actionfraud.police.uk