This document describes an approach to improving spam detection through the use of deterministic finite automata (DFA) rules to match spam patterns before classification. The author's approach aims to gain accuracy and performance over the common methods by using DFA rules to detect spam URLs, file types, and IP addresses. Naive Bayes classification is then used and can achieve 94% accuracy but the author's method improves it by another 4% through the pre-filtering with DFA rules. The full open source C++ project for email auditing is available on GitHub.