Spot the Signs. You may receive this reaction if you're a high_ranking executive or director. These positions can be difficult to replace quickly, so it may be worth it to your company to tempt you to stay rather than letting you go without a fight. It can also happen if you have extremely specialized knowledge that would make it challenging to replace you. On the other hand, if you're in an entry_ or mid_level position, and someone could be hired into your position without much trouble, it's less likely your boss will put up a fight__and a counteroffer.
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.