I would love to see an option that server admins could enable which would prevent new joins to the server from sending a DM to anyone other than a moderator for at least 2 hours.
What it would solve:
Spam bots or trolls who join a server will often immediately start moving down the online member list and sending the same copy pasta junk to everyone they can. Having an option like this would allow legitimate new members to contact mods if needed but prevent other members from getting harassed.
Why current options don't suffice:
Current options for DMs are member specific, and only allow you to turn off all DMs or only allow DMs from people you share a server with. This means you either can't get contacted at all, or you can get bothered by anyone you share a server with - there needs to be a middle ground.