A channelnobody shouldpost in.

VoidSentry bans self-bots and hijacked accounts the moment they write in a trap channel, before they reach the rest of your server.

Free and open source. Works on as many servers as you like, each with its own settings.

The kind of messages trap channels catch

VoidSentry right now

Live totals from the bot, refreshed every minute. They are counts only and contain no personal data.

Add VoidSentry to your server
Use the invite link. It asks for Ban Members, Manage Messages and the permissions needed to post in channels. Move the bot's role above the members it should be able to ban.
Turn a channel into a trap
Open the channel and run /setup-trap. The bot clears it and posts a clear warning. Add as many trap channels as you want.
Choose where bans are logged
Run /add-logchannel in a private moderator channel. Each ban is logged there with the account's age, roles and what it wrote.

An instant ban is only useful if mistakes are rare and fixable.

Admins are never banned: Administrators and any roles you exempt are skipped. Their message is just removed.
Dry-run mode: Turn it on to see what would be banned without banning anyone. Good for testing a new trap.
Failures are reported: If a ban can't happen because of missing permissions or role order, the bot says so in your log channel.
Settings per server: Trap channels, log channel, ban reason and how much history is deleted are set separately on every server.
The user is told why: Before the ban, the bot sends the user a message with the server name and the reason, when their DMs allow it.
Mistakes are reversible: Use /unban to lift a ban. The history stays so you can see what happened.

Commands marked "Administrators" need the Administrator permission on your server.
Command	Who can use it	What it does
/help	Everyone	Lists all commands.
/setup-trap	Administrators	Makes the current channel a trap, clears it and posts the warning.
/add-logchannel	Administrators	Chooses the channel where bans are logged. Any channel name works.
/remove-logchannel	Administrators	Stops posting ban logs.
/trap-settings	Administrators	Shows or changes trap channels, ban reason, history deleted on ban, dry-run mode and exempt roles.
/bans	Administrators	Shows your server's ban history, searches by user ID and shows statistics.
/ban-info	Administrators	Looks up a ban on your server by user ID.
/unban	Administrators	Lifts a ban by user ID.
/status	Administrators	Shows uptime, ping and your server's ban numbers.

Only what it needs to keep a ban history. The full details are in the privacy policy.