Email spam, also known as junk email or unsolicited bulk email(UBE), is a subset of electronic spam involving nearly identical messages sent to numerous recipients by email. Clicking on links in spam email may send users to phishing web sites or sites that are hosting malware. Spam email may also include malware as scripts or other executable file attachments. Definitions of spam usually include the aspects that email is unsolicited and sent in bulk In order to overcome spam problem many researchers have been conducted and various method of anti-spam filtering have been implemented. A spam filter is a set of instruction for determining the status of the received email. Spam filters are used to prevent spam email passing through the recipient. The main challenge is how to design an effective spam filter that allows desired email to pass through while blocking the unwanted email.