Is backbiting and tale-bearing permissible against an evildoer?

Talebearing (namima) is the act of conveying speech to cause discord between two people. It is forbidden among Muslims, including the transgressor, as it is impermissible to sow enmity between one Muslim and another. A severe warning has been reported for the talebearer in the hadith: "A talebearer will not enter Paradise," and that the perpetrator will be punished in the grave.