What do you mean by 'fetches them out of band'?

It downloads them and stores in serverside cache before you ever open the email

	▲	philipwhiuk an hour ago \| parent \| next [-]
		That does mean the email address exists though which was what HSBC was questioning.
	▲	nkrisc 4 hours ago \| parent \| prev [-]
		Frankly the best outcome as it makes them useless.