Complex sentence: The integration of a framework for content scanning that happened in the 4.x releases, which allowed for easier integration of anti-virus and anti-spam measures, this made Exim very suitable for enforcing diverse mail policies.
Split into simpler sentences: The integration of a framework for content scanning, which allowed for easier integration of anti-virus and anti-spam measures, happened in the 4.x releases. This made Exim very suitable for enforcing diverse mail policies.