Siden en vigtig pakke blev sendt til den forkerte adresse, skriver jeg altid postnummeret rigtigt.

Here siden means since in the time sense, more like ever since.

So the idea is:

Ever since an important package was sent to the wrong address, I always write the postal code correctly.

It is not mainly giving a reason in the same way as because. It is saying that the past event became a turning point, and from that time onward the speaker changed their behavior.

A useful contrast is:

• fordi = because
• siden = since / ever since in a time-related sense

So this sentence is about a continuing habit that started after that past event.

This is because of the Danish V2 word order rule in main clauses.

In Danish main clauses, the finite verb usually comes in second position. Here, the whole opening clause:

Siden en vigtig pakke blev sendt til den forkerte adresse

comes first. After that, the finite verb of the main clause must come next:

skriver

and then the subject:

jeg

So the structure is:

[Fronted element] + [finite verb] + [subject] + ...

That is why you get:

Siden ..., skriver jeg altid ...

and not:

Siden ..., jeg skriver altid ...

This is very common in Danish and often feels unusual to English speakers.

Blev sendt is the past passive.

• blev = past tense of blive
• sendt = past participle of sende

Together, they mean was sent.

So:

en vigtig pakke blev sendt til den forkerte adresse = an important package was sent to the wrong address

This is passive because the sentence focuses on the package, not on who sent it.

Compare:

• Nogen sendte pakken = Someone sent the package
  active

• Pakken blev sendt = The package was sent
  passive

This is about definiteness and adjective endings.

1. en vigtig pakke

This is an indefinite noun phrase:

• en = a
• vigtig = important
• pakke = package

So it means an important package.

2. den forkerte adresse

This is a definite noun phrase:

• den = the
• forkerte = wrong
• adresse = address

So it means the wrong address.

In Danish, when an adjective comes before a definite noun, it usually gets -e:

• en forkert adresse = a wrong address
• den forkerte adresse = the wrong address

That is why it is forkerte here, not forkert.

Postnummeret is the definite form of postnummer.

• postnummer = postal code
• postnummeret = the postal code

In Danish, the definite article is often attached to the end of the noun:

• en bil = a car

• bilen = the car

• et postnummer = a postal code
• postnummeret = the postal code

Here the speaker means the postal code in the general practical sense, so Danish naturally uses the definite form:

jeg skriver altid postnummeret rigtigt = I always write the postal code correctly

English often uses the as a separate word, while Danish often builds definiteness into the noun.

Because the sentence describes a current habit that started after a past event.

The past event is:

en vigtig pakke blev sendt til den forkerte adresse = an important package was sent to the wrong address

The result is a habit that is still true now:

skriver jeg altid postnummeret rigtigt = I always write the postal code correctly

So the tense choice is very natural:

• past tense for the one completed event
• present tense for the ongoing habit

English does the same thing:

Ever since that happened, I always write the postal code correctly.

Here rigtigt means correctly.

It comes from the adjective rigtig, which can mean correct or right.

• et rigtigt svar = a correct answer
• at gøre noget rigtigt = to do something correctly

In this sentence, rigtigt is being used adverbially, describing how the speaker writes the postal code.

So:

jeg skriver postnummeret rigtigt = I write the postal code correctly

The -t form is often used when an adjective functions like an adverb in Danish.

Their positions are normal for Danish sentence structure.

altid

Altid is a time/frequency adverb: always.

In the main clause, after the verb and subject, it often comes before the object:

skriver jeg altid postnummeret ...

That is a very natural placement.

rigtigt

Rigtigt describes how the action is done, so it comes after the object here:

postnummeret rigtigt

So the pattern is roughly:

verb + subject + frequency adverb + object + manner adverb

In this sentence:

• skriver = verb
• jeg = subject
• altid = frequency adverb
• postnummeret = object
• rigtigt = manner adverb

Yes. In standard Danish, a comma is used between the subordinate clause and the main clause.

So:

Siden en vigtig pakke blev sendt til den forkerte adresse, skriver jeg altid postnummeret rigtigt.

The opening siden clause is subordinate, and the rest is the main clause, so the comma separates them.

This is one of the things English speakers often notice, because Danish comma rules do not always match English punctuation habits exactly.

Because pakke is a common gender noun, so it takes en, not et.

In Danish, nouns are mainly either:

• common gender: usually with en
• neuter gender: usually with et

So:

• en pakke = a package
• en vigtig pakke = an important package

If a noun is neuter, you would use et and the adjective would often get -t in the indefinite singular:

• et hus = a house
• et vigtigt hus = an important house

But pakke is not neuter, so en vigtig pakke is correct.

Yes, you could say korrekt, and it would still make sense:

... skriver jeg altid postnummeret korrekt.

That would mean basically the same thing: I always write the postal code correctly.

The difference is mostly one of tone and style:

• rigtigt often sounds more everyday and natural
• korrekt can sound a bit more formal or precise

In ordinary speech, rigtigt is very common and natural here.