It also starts the clock for your boss and your company, kicking off the transition plan of training, hiring, and otherwise covering your impending departure. The bad examples here are all too vague. With the last one, you're aligning yourself with company policy, which is good, but it still doesn't tell the reader how much notice that actually is. Be as specific as possible on the time you have between now and your last day.
Spot the Signs. Again, you may receive this response if you have specialized knowledge that would make it difficult or time_consuming to hire your replacement__or if it would be helpful for you to be actively involved in that search.