The Writing Style Verification adds an additional layer of security to corporate email messages. Trend Micro considers the writing style of a person as their "Biological-ID" (or "Bio-ID). The writing style "Biological-ID" is generated based on the historical data of user email messages. Trend Micro scans old email messages of desired users to learn their particular writing style, and creates a model for each user. The subsequent incoming email messages are then compared with the existing models of each user to determine the authenticity of these email messages.