From the security point, low-cost domain names and simplified registering procedures present a potential threat. Malicious attackers could register a domain to use in a single attack campaign and then discard it. At some point, the malicious domain will be red-flagged by the reputable service, but by that time the attacker has moved onto the next one. This creates the difficult and inefficient task to detect the malicious domain. In this paper, the search engine creditworthiness algorithm is used to detect malicious domains. This algorithm is created for bot detection in a local network. In an experimental study algorithm is tested as a detection system for malicious domain found in spam. With the analyzation of the URLs in the e-mail body known fraud or hoax spam can be blocked at the entrance of the mail server or even the local network.