Yahoo! Inc. (NASDAQ: YHOO) is an American public corporation headquartered in Sunnyvale, California, (in Silicon Valley), that provides Internet services worldwide. The company is perhaps best known for its web portal, search engine (Yahoo! Search), Yahoo! Directory, Yahoo! Mail, Yahoo! News, advertising, online mapping (Yahoo! Maps), video sharing (Yahoo! Video), and social media websites and services.

This SonicWALL signature identifies legitimate Yahoo! Mail traffic.