I ran an exit node at home for a couple months. Within minutes of my dynamic IP being updated from my ISP, cloudflare could figure out that I was an exit node, and then would fail to differentiate my own, non tor traffic, with that of the traffic exiting my node. The result being every single cloudflare backed website will hit you with a captcha on every page you view.

My ISP would also randomly shut off my connection with some vague email about having compromised computer on my network i needed to fix. I'd have to call and make up some story to get them to turn my internet back on.

Essentially all kinds of people associate TOR with unsavory activity and as such put hoops to jump through when accessing stuff through tor. When you host an exit node your non tor traffic is considered to be outbound TOR traffic based on the IP the traffic originates from.

I cant imagine what would happen if I ran a node on the same network as our email server. I have to assume that we'd get blacklisted for spam quick if our mx resolved to a tor exit node IP.

Then there's the whole issue of more or less being guaranteed to be complicit in the distribution of CP. With really only safe harbor laws protecting you.