This small addon is intended to block group invite attempts from a type of spam bot which tries to invite you to send party messages saying you won a Spectral Tiger and need to access a website to retrieve it.
Those bots are generally DeathKnights lvl 55 and their names try to mimic the "Blizzard" name creating variations such "Bllizard", "Blizzardi", "Biizard", etc.
The addon declines the invite and add the person to your ignore list.