Very simply; this plugin stops all chat from players who do not have the correct permissions.

This also includes a variety of 'chatty' commands, including /me, /msg, /tell, /reply, /m, /t, and /r. It also optionally bans players who tried to chat a 'forbidden' phrase. And last, but not least, it is compatible with Vault and BanHammer, but does not require either. If you are using Vault then your known players are completely immune to moderation! If you are using BanHammer, so will this; Failing that it bans both the IP and Playername, and then kicks the player with the reason 'SpamBot'

I developed this one after the server I develop for encountered some nasty spam attacks. To combat this 'new problem' for the MineCraft community I've taken inspiration from one of the oldest venues of public chat still in use to this day. This plugin is functionally the same as using the moderated, and voiced flags of IRC. Now I've been lurking on IRC for over a decade now, and I know IRC networks have been dealing with chat spam for a long time. Their solution is both simple and elegant; Don't deal with the spam, stop it completely.

Usage:

/moderate | Shows the moderation status, and banphrase.
/moderate on | Puts the server into moderated mode.
/moderate off | Takes the server out of moderated mode.
/moderate phrase <banphrase> | Sets the optional [banphrase]
/moderate phrase | Clears the banphrase
/moderate spamme | Toggles the users reciept of suppressed messages on and off

Permissions: If Vault is installed it will be used to check for permissions, otherwise SuperPerms will be used. Ops are always considered to have both nodes;

omgwtfhax.moderate.bypass - Allowed to chat while in Moderated mode.
omgwtfhax.moderate.moderate - Allowed to use the moderating functions of the plugin.

Upcoming Features:

Nicer plugin page ;P
Configurable toggle for each thing we monitor.
Configurable strings for localization.
Storing the names, and IPs of banned spambotters in a web accessible database to simplify the process of appealing a ban should an innocent player get caught in the crossfire.

OMGWTFHAX: Emergency Chat Moderation