There have been multiple mods for filtering the chat. There was a mod that made a second chat screen and one with tabs for each channel. But at the moment they dont get updated anymore and they are out dated.
I'm searching for mod that changes the chat. Filters for example [announcement], Spam filters that add [x2]. The best thing would be a second chat where I can put filtered channels.
Channels I use atm are, local, general, pm. socialspy, towny NC & TC, towny spy, announcement, mail and staff channels sm mod admin.
The closest that exists in Vanilla is F3 + D to clear chat and otherwise plugins you get on with servers like Bukkit (not sure if more so hides the chat or removes it/filters it based on what you want to see like your team/faction or other things and you not needing to reply on tell or tellraw commands), more so than a mod. I'd check a few server plugins and see what options there is, but otherwise I think this would be a good idea either way if you don't use Bukkit and want a mod for this sort of thing.
Otherwise is there anything possible with any admin/factions and otherwise like mods at all? Like does have FTB Utilities or other mods have this option, I'd check some of those. I'm not too familiar with any but just saying.