Ensure that the exterior mahogany door is clean and dry. The door should be placed in a well-ventilated area that will remain dry until you are done staining it.
Sand your mahogany exterior doors with fine grit sandpaper to scruff the surface of the door.
Apply a layer of stain and filler combination to the entire door with a high quality paintbrush. The stain and filler combination can be found at building supply stores. It will help fill the pores of the wood and create a smooth base. Allow the filler to dry for four to six hours.
Stain the exterior door with an alkyd-resin based stain and sealer combination using a high quality paintbrush. Wait 4 to 6 hours for the stain to dry.
Sand the door lightly with fine grit sandpaper and apply a second coat of stain. Again, allow the stain to dry for four to six hours. If a third coat of stain is required, sand the door lightly between coats.