Why does SMF tinker with DKIM?

[StrangePeanut]

DKIM was developed with email forwarding in mind. DKIM validity of forwarded email should not break. Why does SMF decide to tinker with DKIM when it should be left alone?

Since the README.md does not include any use cases examples, I apologise if I am missing a legitimate use case. It would be great if an explanation could be added to README.md in this case.

Been looking for a simple email forwarding solution and I am so glad to have found SMF. Many thanks for this brilliant solution to email forwarding.