Are we even sure the trophy reductions for your guild are related to the mail exploit? Perhaps the player was banned for botting instead of exploiting the mail? If so then your guild would definitely lose all of the trophies gained illicitly.
@Sirrian @Saltypatra @Cyrup can we at least get some kind of verification that guild trophy loses were or were not related to the mail bug exploit punishments? I know policy is you can’t/won’t discuss cheating investigations but trophy reductions feel completely unrelated as there isn’t really a way to translate gems directly into trophies. Please put the speculation & subsequent “discussion” of this issue to rest before people go ape 
Edit: I see someone also started a new post about this issue as well while I was reading/posting here