I suggest adding /ignore to Hellblock to reduce the amount of fighting/drama on the server. This would be applied for defaults+. I believe this is just a forgotten perm, that isn't op Now for /mail, I think that moderators should have /mail send permissions, while players can have the /mail read and /mail clear perms. This would be helpful for transferring important messages to the players while they are offline (Useful for moderators) Thanks for reading!
The permissions were added to all groups when I was running Hellblock so I don't know why it was changed but it was obviously changed for a reason.