Dolurrh the Realm of the Dead is a hopeless gray waste where mortal souls go after death. It is not a reward, nor a punishment, it simply is. Dolurrh is timeless, and people who visit Dolurrh are slowly overcome with apathy and eventually fade, turning into a shade.
Dolurrh is Eberron's realm of the dead, where most mortals go when they die. For those on the plane of Dolurrh, colors become grayer and less vivid, and visitors experience a feeling of ennui. Those that visit the plane sway under its influence, losing the desire to leave, and eventually forgetting their previous lives. These visitors eventually become shades, and native to Dolurrh. For visitors trapped in Dolurrh, only the most powerful of magics can free them.
When one dies, one's soul travels to Dolurrh. However, it is possible to use powerful resurrection magics to bring the soul back from Dolurrh to the Material Plane. In addition, it is possible to bring a soul back to the Material Plane via plane shifts or fixed portals; though doing so would subject the revivers of the risks of visiting the Realm of the Dead. It must be noted, though, that the maruts actively discourage resurrection in this manner.
Though it is the realm of the dead, Dolurrh is not the home of the Keeper, the god of the dead from the Dark Six. In fact, the Keeper tries to snatch wayward souls on the way to Dolurrh. He keeps those souls as servants.
Because the walls between Eberron and Dolurrh are thinner than other planes, it is possible to draw upon their energies. The dragon Arstyvrax draws upon the energies of Dolurrh to power his necromantic research; while the lich queen Vol wishes to destroy these boundaries entirely, and become queen of the realm of the dead.
Though most souls travel to the Realm of the Dead, there are some that do not. Those souls beholden to the Silver Flame will join it upon death. It is said that if the dragon god Chronepsis deems a dragon worthy, he will bring the dragon to the realm of the Sovereigns instead of Dolurrh.The Path of Light promises those amongst the Inspired an afterlife outside of Dolurrh. Some organizations will use undeath to prevent a soul going to Dolurrh, such as the Blood of Vol, the nation of Karrnath, and the Undying Court. And no ones knows where the souls of the warforged go, if anywhere, since no warforged soul has been found in Dolurrh.