If you choose to live behind gates, there are going to be issues. Any entrance that needs a fob or a code is sometimes going to result in packages with 'address inaccessible' written on. Agency or non-regular staff will not know your code. Sometimes you will just get a P739 card with your regular post, because we have stopped sending packets out repeatedly as this is a waste of everybody's time.
If your gate is open, I will leave it open, since you probably don't care. If it's shut then I will shut it.
People who make formal complaints about their gate probably need to be grateful they have so few problems in their life that it matters.
(Disclaimer: this A to Z is not official Royal Mail advice, except by coincidence.)
Stay safe. Be kind. You can't keep the world out with a locked gate.