In the old days a person's address was usually a piece of public information, and one could send a letter to more or less anyone without thinking one had transgressed basic standards of civilisation. One might not get a reply, or it might not even get read, but that was a different matter.
Now that we are most of us on the internet, knowledge, or, worse, use of a person's email address without their explicit sanction is regarded as the most intimate kind of personal violation, even though an email can be consigned to oblivion with a single jab of a finger, whilst a letter had to be torn and thrust into the fire (preceded of course by an exhaustive risk assessment).
We should take a lesson from the eighteenth century, when they managed to combine a pronounced idea of the Polite with the most pointed kind of personal communication and remark, and decorum and scurrilousness could rub shoulders. It is perhaps because we nowadays have no real notion of politeness that we hem ourselves around with absurd protocols of appropriateness.
Perhaps in these times of unemployment we should all be enabled to recruit the kind of personal 'filter' that royalty has long relied upon: "Her Majesty desires me to convey..."