https://www.newscientist.com/article/2165699-how-you-and-your-friends-can-fight-back-against-online-trolls/

Tackling trolls with a little help from your friends. A “friendsourcing” tool called Squadbox lets people use their friendship group to filter abusive messages sent to them by online trolls.

If someone is being targeted with abuse, Squadbox allows friends, support groups or other trusted parties to access their email account to act as personal moderators. Known contacts can also be whitelisted so their emails go straight through without moderation, or a specific email address can be blacklisted if the harassment comes from a single source.