Inconsistency in sender knowing the exact location of the recipient when sending an owl

Question

Many times we have seen the address on the post received through an owl, exact even down to the room in which the recipient is located. For example

In Harry Potter and the Philosopher's Stone:

Harry picked it up and stared at it, his heart twanging like a giant elastic band. No one, ever, in his whole life, had written to him. Who would? He had no friends, no other relatives -- he didn't belong to the library, so he'd never even got rude notes asking for books back. Yet here it was, a letter, addressed so plainly there could be no mistake: Mr. H. Potter The Cupboard under the Stairs 4 Privet Drive Little Whinging Surrey

But the same is not true when Harry is writing letters/sending owls. He seems to speculate.

E.g., in Harry Potter and the Goblet of Fire:

“Good thinking!” said Ron, his expression clearing. “I bet Sirius’ll know what to do!” “I hoped he’d get back to me quickly,” said Harry. “But we don’t know where Sirius is . . . he could be in Africa or somewhere, couldn’t he?” said Hermione reasonably. “Hedwig’s not going to manage that journey in a few days.”

So why is this not consistent? Does Harry not know the skill of sensing the receiver's location or is there something I'm missing?

Answer 1

We are getting a little caught up in the details here and forgetting that the most specific addresses are all to Harry in Sorcerers stone.

Yet here it was, a letter, addressed so plainly there could be no mistake:

Mr H. Potter

The Cupboard under the Stairs

4 Privet Drive

Little Whinging

Surrey

Later

She held up a letter so they could read the green ink address:

Mr H. Potter

Room 17

Railview Hotel

Cokeworth

These letters are the exception, and not the rule. Do not forget Hagrid was actively sending these letters to Harry, and physically following the Dursleys around the country side. He always knew exactly where Harry was.

"I was allowed ter do a bit (magic) ter follow yeh an'get yer letters to yeh an' stuff -- one o' the reasons I was so keen ter take on the job --"

Every other instance of letters we see are either sent broadly with owls to just the recipient, maybe including their street address.

Why were Harry's Hogwarts Acceptance Letters Not Sent Directly To Him? review my answer to this for details.

The only other exception i know is the letter from Percy to Ron. But that letter was meant to be received in the gryffendor common room, not in the morning owl post.

Do owls deliver only in fixed daily windows? review my answer here for further details.

Ron, I want to give you some advice, which is why I am sending this at night rather than by the usual morning post. Hopefully, you will be able 'o read this away from prying eyes and avoid awkward questions.

So other then the letters addressed specifically to Harry in book 1, we only see vague letters with recipients names, and potentially address, and in very rare cases the owls were to deliver to specific rooms at specific times.

Harry also states that at least for Hedwig address's are not important.

Harry’s owl had never yet failed to deliver a letter to any- one, even without an address.

Answer 2

I'm not sure it's made explicit in canon, but we can probably make a decent guess.

Both Hogwarts correspondence and individual mail seems to be capable of being addressed in minute detail.

He crossed to the window and opened it; Hermes flew inside, landed on Ron's essay and held out a leg to which a letter was attached. Ron took the letter off it and the owl departed at once, leaving inky footprints across Ron's drawing of the moon Io.

'That's definitely Percy's handwriting,' said Ron, sinking back into his chair and staring at the words on the outside of the scroll: Ronald Weasley, Gryffindor House, Hogwarts. He looked up at the other two. 'What d'you reckon?

'Open it!' said Hermione eagerly, and Harry nodded.

—Harry Potter and the Order of the Phoenix

Petunia Dursley receives a similar letter when the Dursleys are about to throw Harry out:

'Let go of it, Petunia!' roared Uncle Vernon. 'Don't touch it, it could be dangerous!'

'It's addressed to me,' said Aunt Petunia in a shaking voice. 'It's addressed to me, Vernon, look! Mrs Petunia Dursley, The Kitchen, Number Four, Privet Drive -

She caught her breath, horrified. The red envelope had begun to smoke.

—Harry Potter and the Order of the Phoenix

However, the three instances that we know of in which a letter was minutely addressed were both official correspondence of a sort: letters from Hogwarts to Harry, and a letter from Percy (at the time a high-up Ministry employee) to Ron, and a letter from Dumbledore (headmaster of Hogwarts) to Petunia Dursley.

I think it likely that this is reserved for official correspondence. That's not to say that a private individual couldn't do things this way, of course, but Harry and others always seem to address their letters by hand.

It is also true that many magical missives seem to be able to find their targets without the sender knowing the recipient's location. For example, Harry is able to send letters to Sirius via Hedwig in Goblet of Fire, even though he does not know Sirius's location.

I suspect that the address must be automagically generated when the letter nears its recipient. After all, if Percy were able to know the location of anyone in Hogwarts from hundreds of miles away, that would seem like a pretty big security loophole in the protective spells surrounding the castle. If the Ministry could simply generate a letter with Sirius's precise location on it, catching him would certainly be a lot easier.

I think it more likely that the address is simply generated upon arrival, or something along those lines.

Owls, of course, are very good at getting letters to people, even when the sender knows nothing about the recipient's address (as in Harry's case). Sirius must have had some additional security, obviously, to prevent just any owl from tracking him down, but it is not difficult to conceive what this might be (something like the spells Hermione used to hide the Trios's exact location in Deathly Hallows).

The key thing is that letters can have magically detailed addresses without allowing the sender to know anyone's location; in fact, this seems most consistent with the way such mail works in the books.

In the case of Harry's letter to Sirius, first, we don't know that Harry hasn't placed a spell on the envelope to render it nicely addressed when it arrives, and second, doing so would not necessarily give him Sirius's location.

Answer 3

The address on Harry's letter was only because Dumbledore didn't want there to be any confusion about who the letter was for, and also because he had to make sure that the owl, who did not know where the Dursleys lived, found Harry. He knew all along where Harry was, because he's Dumbledore. And he wrote the letter and address. When Harry writes to Sirius, he, the writer, does not know the location, but Hedwig knows Sirius already and can therefore track him down. The owls are the one with the tracking ability, not the wizard. The address is only specific if the writer knows the location.