Keep in mind that as a way to mark her territory and feel more secure, a cat is likely to urinate outside the box or spray and scratch door posts.
You may need to do more than close the blinds since cats are persistent creatures. For instance, purchase dark window clings to cover the window. Use them on the part of the window at your cat’s level, and leave the top of the window open for a view.
Try providing your cat with some high shelves that she can easily get up on or a tall cat tree. She may feel safer up on these high spots because she will be up off the ground and better able to see an intruder coming. You should also provide some hiding spots in each room, such as cardboard boxes with cat sized holes cut into them. Having a safe place that she can retreat to will also increase your cat’s sense of security.
Obviously, if your cat tries to attack you, back away, and let it have some space.
Try using a diffuser in the room where your cat most often sees the outdoor cat. The scent should help keep your cat calm. You can find these diffusers at pet stores or online.
Ask your vet for a recommendation for a behaviorist.
These deterrents will need to be renewed regularly, particularly after it rains. Also, renew them if you notice cats coming around. You may need to do it as often as twice a month. You just need enough to make a steady border around your yard. You can also buy a cat repellent spray at places like feed stores.
You could say, “I don’t want to cause issues between us, but I was wondering if you knew that your cat enjoys taunting the indoor cats in the neighborhood. For instance, he loves spraying on our porch, which drives our indoor cat crazy. "
