Die stawende dokument is aan die e-pos geheg.

Because die is the Afrikaans definite article, and it is used for all genders and for both singular and plural nouns.

So:

• die stawende dokument = the supporting document
• die e-pos = the email

Unlike English, Afrikaans does not have different forms like the / a / an based on sound, and unlike some other languages, it does not change the definite article for masculine, feminine, or neuter nouns.

Stawende means supporting, substantiating, or confirming.

It comes from the verb staaf, which means to substantiate, to support with evidence, or to confirm.

So a stawende dokument is not just any document; it is a document that serves as evidence or backing for something. In formal or administrative language, this often refers to a supporting document.

In Afrikaans, many present-participle-like adjective forms end in -ende.

So from staaf, you get stawende when it is used adjectivally:

• ’n stawende dokument = a supporting document

This -ende pattern is common in formal Afrikaans adjectives derived from verbs.

Is geheg is a passive/result structure meaning is attached.

• is = is
• geheg = past participle of heg (to attach)

So the structure works like this:

• Die dokument is geheg = The document is attached

This is very similar to English.

In Afrikaans, passive constructions often use:

• word + past participle for the action/process
• is + past participle for the resulting state or a general present statement

So is geheg here focuses on the fact that the document is attached.

That is normal Afrikaans word order.

In a main clause, the finite verb usually comes in the second position, so is appears early:

• Die stawende dokument is ...

The past participle or main verbal element often goes later, frequently at the end:

• ... aan die e-pos geheg

So the sentence follows a very typical Afrikaans pattern: subject + finite verb + rest of sentence + past participle

Here aan means to.

With geheg, Afrikaans commonly uses aan to show what something is attached to:

• aan die e-pos geheg = attached to the email

So if you want to say what an attachment is connected to, aan is the expected preposition.

Because the idea is attached to the email, not inside the email.

Afrikaans uses aan with heg / geheg in the same way English uses to with attach:

• attached to the email
• geheg aan die e-pos

If you said in die e-pos, that would suggest something is in the email message itself, which is a different idea.

E-pos is the standard Afrikaans word for email.

It is written with a hyphen because Afrikaans commonly uses hyphens in formations like this, especially with shortened or letter-based first elements.

So:

• e-pos = email
• e-posadres = email address

You may also hear people use English-influenced forms in casual speech, but e-pos is the standard Afrikaans form.

It is singular.

You can tell this from the context:

• die stawende dokument = the supporting document

The plural would usually be dokumente:

• die stawende dokumente = the supporting documents

Notice that die would stay the same even in the plural.

Yes, you may hear variants like that, but they are not exactly the same in tone or structure.

Common possibilities include:

• Die stawende dokument is aan die e-pos geheg.
• Die stawende dokument is by die e-pos aangeheg.

The version with aan ... geheg is a very natural standard way to say something is attached to an email.

The version with aangeheg is also common, especially in administrative or computer-related contexts, because aanheg means to attach.

So both are understandable, but the original sentence is perfectly idiomatic.

Yes, it sounds fairly formal and administrative.

Two things make it sound formal:

• stawende dokument is a formal expression
• the passive structure is ... geheg is common in official writing

In everyday casual speech, someone might say something simpler, depending on context, but this sentence is very natural in emails, office communication, applications, and official documents.

You would replace die before stawende dokument with ’n:

• ’n stawende dokument is aan die e-pos geheg.

That means:

• A supporting document is attached to the email.

But notice that die e-pos can stay definite if you mean a specific email.

So:

• die stawende dokument = the supporting document
• ’n stawende dokument = a supporting document