There's an extension for that in 3.1 but I'm not sure if there ever was a mod in [3.0.x] MOD Database Releases
. If there isn't one you may have to upgrade to 3.1 as the 3.0 mods forums are now closed. Which version of phpBB are you using?
Edit: I've just had a search and there's this mod
. Does that help?
That is good to know, we are running 3.0.14, which I believe is the last version of 3.0.x before 3.1. If the feature is available as an extension in 3.1.x I we will look into to updating, we're just scared to as we don't want things to break.