They have possibly been informed of the source of the smell, because they don't complain. When he's done with breakfast they hear the click of the mail slot and the flop of letters on the doormat.

"Get the mail, Dudley," says Uncle Vernon from behind his paper.

"Make Victor get it."

"Get the mail, Victor."

"Yes, Uncle Vernon."

He gets the mail.

Three things lay on the doormat: a postcard from Uncle Vernon's sister Marge, who's vacationing on the Isle of Wight, a brown envelope that looks like a bill, and—a letter for Victor.

...that's terrifying. Who would send Victor a letter?

He picks it up and reads the front:

Mr. V. Evans
The Cupboard under the Stairs
4 Privet Drive
Little Whinging
Surrey

So not only is someone sending him letters, they know about the cupboard. It has been very clear to Victor for a very long time that no one is to know about the cupboard. If he lets Uncle Vernon or Aunt Petunia see this, will they think he told? But if he tries to hide it, what if they know about it already?

The letter is very thick and heavy, the envelope made of a kind of paper he can't remember ever seeing before, yellowish and mysterious. It's addressed in emerald green ink, in fancy handwriting, and sealed in wax like something out of a storybook. There is no stamp. How did it get here? Letters need stamps on them to go through the post. Did someone just write it and put it through the mail slot? Is someone spying on him and writing him strange letters and putting them through the mail slot themselves? No, he doesn't think the Dursleys could possibly know about this. They aren't the sort of people who would be friends with anyone who would do that.

It's been a few seconds and any moment Uncle Vernon is going to yell at him. He makes up his mind. The postcard and the bill go in one hand, the letter in the other, and he walks quickly back to the kitchen and hands Uncle Vernon all of the post that is for him and turns to go to his cupboard, hoping that they will all just be ignoring him like they usually do and no one will ask what that is in his hand -

No one spares him a glance.

"Marge's ill," Uncle Vernon informs Petunia. "Ate a funny whelk..."

He gets the letter safely into his cupboard and sits on his bed and stares at it.

What should he do?

If he reads it - will the spy know? How are they spying on him? Will they cause trouble? If he doesn't read it will they cause more trouble? Maybe he should destroy it somehow and try to forget it ever happened.

Well, before he wastes any more time trying to decide, he should go wash the dishes. He stuffs the letter under his tiny mattress and goes back to the kitchen and cleans up his plate, pausing in front of the sink.

"Should I do the washing-up later so I don't interfere with... this?" he asks hesitantly, glancing at Aunt Petunia and gesturing to the metal tub full of horrible-smelling grey water and rags.

"I'll do it. Those are your new school uniforms."

...not worth commenting. He nods and goes back to his cupboard.

The letter is right there, under his mattress. Sealed with wax. Addressed in emerald green ink.

If there is someone spying on him, they might assume he's going to read the letter. And then they might do things based on that assumption, and they might be angry with him if it turns out to be false.

Carefully, hesitantly, he opens it.

The inside is just as fancy as the outside, written with green ink. The first page reads:

HOGWARTS SCHOOL
of WITCHCRAFT and WIZARDRY

Headmaster: Albus Dumbledore
(Order of Merlin, First Class, Grand Sorc., Chf. Warlock,
Supreme Mugwump, International Confed. of Wizards)

Dear Mr. Evans,
We are pleased to inform you that you have been accepted at Hogwarts School of Witchcraft and Wizardry. Please find enclosed a list of all necessary books and equipment.
Term begins on 1 September. We await your owl by no later than 31 July.

Yours sincerely,

Minerva McGonagall
Deputy Headmistress

This is a problem.

They're expecting him to send an owl. He doesn't have an owl and would have no idea how to send one by post if he did. Or maybe the owls carry the post, and that's why there's no stamp? Who knows? They're wizards. Which is the second of the many problems that this is. Uncle Vernon and Aunt Petunia are going to be so upset.

All right, think. What does he do. Does he - try to go to the magic school, somehow? No, even if he knew where to get an owl, the Dursleys would never let him attend such a ridiculous school. He'll just have to hide the letter and hope they don't send any more. And get the mail as soon as it arrives every single day from now on in case they do.

There are more things in the envelope, if he cares to look.

Yes, they mentioned a list of necessary books and equipment. He'd better read everything and memorize it all, just in case the wizards show up and want to know why he hasn't answered their letter.

The list is also in fancy ink:

HOGWARTS SCHOOL
of WITCHCRAFT and WIZARDRY

UNIFORM
First-year students will require

1. Three sets of plain work robes (black)
2. One plain pointed hat (black) for day wear
3. One pair of protective gloves (dragon hide or similar)
4. One winter cloak (black, with silver fastenings)

Please note that all pupils' clothes should carry name tags.

COURSE BOOKS
All students should have a copy of each of the following:
  The Standard Book of Spells (Grade 1) by Miranda Goshawk
  A History of Magic by Bathilda Bagshot
  Magical Theory by Adalbert Waffling
  A Beginner's Guide to Transfiguration by Emeric Switch
  One Thousand Magical Herbs and Fungi by Phyllida Spore
  Magical Drafts and Potions by Arsenius Jigger
  Fantastic Beasts and Where to Find Them by Newt Scamander
  The Dark Forces: A Guide to Self-Protection by Quentin Trimble

OTHER EQUIPMENT
  1 wand
  1 cauldron (pewter, standard size 2)
  1 set glass or crystal phials
  1 telescope
  1 set brass scales
Students may also bring, if they desire, an owl OR a cat OR a toad.

PARENTS ARE REMINDED THAT FIRST YEARS
ARE NOT ALLOWED THEIR OWN BROOMSTICK

Lucinda Thomsonicle-Pocus
Chief Attendant of Witchcraft Provisions

...this is very weird.

But he memorizes the list and carefully folds it back up and puts it and the letter neatly back into the envelope and tucks in the flap since the seal isn't holding it shut anymore, and shoves the letter under his bed again and goes back out to do something useful with his time.

The Dursleys did not actually miss him and don't notice anything out of the ordinary.

Good.

Then he can just pretend it never happened.

Except next morning there's mail again.

"Victor, go fetch the mail."

"Yes, Uncle Vernon."

He goes and fetches the mail and hopes there isn't anything from the wizards.

The only thing there is is, in fact, the letter from the wizards.

...oh no.

And Uncle Vernon knows there's mail so he has to think quickly - should he lie and say there was nothing, lie and say it was just an advert - no, it's bad when they think he lied about something -

"It's got my name on it," he says in what he hopes is a puzzled tone of voice. "Must not be important. Should I throw it out?"

The best description of what Vernon Dursley does then might be "guffaw," but that probably does not do justice to the full-body experience that was. "Who would be addressing letters to you, boy?"

"I don't know."

Okay, that's as much misdirection as he can get away with. He comes into the kitchen and shows Vernon the letter.

He glances at it dismissively—

—then stares, his face going from red to green faster than a set of traffic lights, and doesn't stop there, going all the way to the greyish white of old porridge. "P-P-Petunia!" he gasps.