Learn Hardcore Greek: Το πακέτο δεν παραδόθηκε χτες, γιατί ο ταχυδρόμος δεν μας βρήκε στο σπίτι. - The package was not delivered yesterday, because the mail carrier didn’t find us at home.

In English you’d normally say The postman didn’t deliver the package, but Greek often uses this passive form: Το πακέτο δεν παραδόθηκε (The package wasn’t delivered).

Why is the negative δεν and not μην here?

Greek uses two main negations: δεν and μην.

δεν is the normal negation for statements:
- Δεν παραδόθηκε = It was not delivered.
- Δεν μας βρήκε = He did not find us.
μην mostly appears:
- in negative commands: Μην μιλάς! (Don’t talk!)
- after some verbs/expressions that take the subjunctive:
  - Θέλω να μην έρθει. (I want him not to come.)

In your sentence we have simple past statements, so δεν is the only correct choice:
Το πακέτο δεν παραδόθηκε χτες, γιατί ο ταχυδρόμος δεν μας βρήκε στο σπίτι.

Can the word order change? For example, can I move χτες or δεν somewhere else?

Basic rules still apply:

δεν must come right before the verb it negates:
- δεν παραδόθηκε (not παραδόθηκε δεν)
- δεν μας βρήκε (not μας δεν βρήκε)

The time adverb χτες is flexible. All of these are grammatical, with slightly different emphasis:

Το πακέτο δεν παραδόθηκε χτες.
Το πακέτο χτες δεν παραδόθηκε. (more emphasis on yesterday)
Χτες το πακέτο δεν παραδόθηκε. (strong focus on yesterday)

You can also move the cause clause:

Το πακέτο δεν παραδόθηκε χτες, γιατί ο ταχυδρόμος δεν μας βρήκε στο σπίτι.
Γιατί ο ταχυδρόμος δεν μας βρήκε στο σπίτι, το πακέτο δεν παραδόθηκε χτες. (more formal / written, fronted reason)

So: you can move χτες and even the whole γιατί-clause for emphasis, but δεν always stays directly before its verb.

What’s the difference between χτες and εχθές? Are both correct?

Both are correct and mean yesterday.

χτες – more common in everyday modern Greek; slightly more informal/spoken.
εχθές – a bit more formal or careful; often seen in writing, but also spoken.

In this sentence you can use either:

Το πακέτο δεν παραδόθηκε χτες.
Το πακέτο δεν παραδόθηκε εχθές.

The meaning is identical.

What does μας βρήκε στο σπίτι literally mean, and why is μας necessary?

Literally, μας βρήκε στο σπίτι means he found us at home.

μας = us (direct object pronoun)
βρήκε = he found
στο σπίτι = at home

Greek needs the object pronoun μας to say whom he found. Without it:

Ο ταχυδρόμος δεν βρήκε στο σπίτι.

This sounds incomplete or wrong, like saying The postman didn’t find at home in English. You have to specify whom he didn’t find:

Ο ταχυδρόμος δεν μας βρήκε στο σπίτι. = The postman didn’t find us at home.

So μας is obligatory here.

What is στο exactly, and how is στο σπίτι different from just σπίτι?

στο is a contraction:

σε + το → στο

So:

σε = in / at / to (preposition)
το = the (neuter article)
στο σπίτι = in/at the house, or simply at home

Differences in use:

σπίτι alone can mean home in a more general sense:
- Είμαι σπίτι. = I’m at home.
στο σπίτι is more explicitly in/at the house:
- Δεν ήμασταν στο σπίτι. = We weren’t at (the) home / in the house.

You could also say στο σπίτι μας (at our house) if you want to make it explicit, but in this context στο σπίτι already implies at home (our home).

Why is it βρήκε and not έβρισκε? What’s the difference?

Both come from βρίσκω (I find), but they are different past tenses:

βρήκε – aorist (simple past), one completed action
- Ο ταχυδρόμος δεν μας βρήκε στο σπίτι.
  → He didn’t find us at home (on that occasion / at that time).
έβρισκε – imperfect (past continuous or repeated)
- Ο ταχυδρόμος δεν μας έβρισκε στο σπίτι.
  → He couldn’t find us at home (repeatedly / for a while).

In your sentence, you’re talking about one specific delivery attempt yesterday, so the aorist βρήκε is the natural choice.

What’s the difference between γιατί and επειδή for “because” here? Could I use επειδή instead?

Both γιατί and επειδή can mean because when introducing a reason:

Το πακέτο δεν παραδόθηκε χτες, γιατί ο ταχυδρόμος δεν μας βρήκε στο σπίτι.
Το πακέτο δεν παραδόθηκε χτες, επειδή ο ταχυδρόμος δεν μας βρήκε στο σπίτι.

In this sentence, both are correct and natural.

Differences:

γιατί has two uses:
- why (question): Γιατί δεν παραδόθηκε το πακέτο;
- because (answer): Γιατί ο ταχυδρόμος δεν μας βρήκε στο σπίτι.
επειδή only means because, not why.

γιατί is extremely common in speech, both as why and because.
επειδή can feel a bit more formal or explicit when giving a reason, especially in writing.

Why is the passive Δεν παραδόθηκε used here instead of something like Ο ταχυδρόμος δεν παρέδωσε το πακέτο?

Both are correct, but they focus on different things.

Το πακέτο δεν παραδόθηκε χτες…
- Topic/focus: the package
- The package is what we’re talking about; who failed to deliver is less important.
- Very natural in Greek when the result is what matters.
Ο ταχυδρόμος δεν παρέδωσε το πακέτο χτες…
- Topic/focus: the postman (his action or failure).

Greek often uses the passive (especially in the aorist) in situations where English might use an active with an agent, particularly when:

the important thing is the result: delivered/not delivered
or the agent is obvious, unknown, or not important

So here, Το πακέτο δεν παραδόθηκε χτες sounds very natural, just like English The package wasn’t delivered yesterday.

Why do we have definite articles το πακέτο and ο ταχυδρόμος? Could we leave the articles out?

In the sentence:

το πακέτο = the package (a specific, known package)
ο ταχυδρόμος = the postman (the specific/regular postman, or the one assigned)

Greek uses definite articles more frequently than English:

Το πακέτο δεν παραδόθηκε.
→ The package wasn’t delivered. (We both know which package.)

Dropping the article would change the meaning or sound unnatural:

Πακέτο δεν παραδόθηκε χτες… – sounds odd; could be understood, but feels like you’re talking about “package” as a category, not a particular one.
Ταχυδρόμος δεν μας βρήκε στο σπίτι. – also odd; could be used in some very specific stylistic contexts, but not as normal speech.

So in normal usage, you need the articles here:
Το πακέτο… ο ταχυδρόμος…