the scammer must be untraceable and irreversible. Otherwise, the victim, once they become aware of the scam, could successfully retrieve their money and alert officials who could track the accounts used by the scammer. Wire transfers via Western Union and MoneyGram are ideal for this purpose. International wire transfers cannot be cancelled or reversed, and the person receiving the money cannot be tracked. Other non-cancellable forms of payment include postal money orders and cashier's cheques, but wire transfer via Western Union or MoneyGram is more common. Anonymous communication Since the scammer's operations must be untraceable to avoid identification, and because the scammer is often impersonating someone else, any communication between the scammer and his victim must be done through channels that hide the scammer's true identity. The following options in particular are widely used. Web-based email Because many free email services do not require valid identifying information and also allow communication with many victims in a short span of time, they are the preferred method of communication for scammers. Some services go so far as to mask the sender's source IP address (Gmail being a common choice), making the scammer's country of origin more difficult to trace. While Gmail does indeed strip headers from emails, it is possible to trace an IP address from such an email. Scammers can create as many accounts as they wish and often have several at a time. In addition, if email providers are alerted to the scammer's activities and suspend the account, it is a trivial matter for the scammer to simply create a new account to resume scamming. Email hijacking/friend scams Some fraudsters hijack existing email accounts and use them for advance-fee fraud purposes. For instance, with social engineering, the fraudster impersonates associates, friends, or family members of the legitimate account owner in an attempt to defraud them. A variety of techniques such as phishing, keyloggers, and computer viruses are used to gain login information for the email address. Fax transmissions Facsimile machines are commonly used tools of business whenever a client requires a hard copy of a document. They can also be simulated using web services and made untraceable by the use of prepaid phones connected to mobile fax machines or by use of a public fax machine such as one owned by a document processing business like FedEx Office/Kinko's. Thus, scammers posing as business entities often use fax transmissions as an