Unifying data is crucial for several reasons: 1. Consistency: Ensures that all departments have access to the same customer information. 2. Personalization: Enables the creation of highly targeted and personalized email campaigns. 3. Efficiency: Reduces the time and effort required to analyze and utilize customer data. 4. Compliance: Helps in adhering to data protection regulations like GDPR by maintaining accurate and up-to-date records.