Geturðu sagt mér hvernig ég á að opna viðhengið í tölvupóstinum?

Geturðu is a very common spoken-and-written contraction of getur þú.

• getur = can / are able to (2nd person singular of geta)
• þú = you

So:

• Geturðu sagt mér ...? = Can you tell me ...?

This contraction is extremely normal in Icelandic. You will also see similar forms like:

• viltu = vilt þú
• hefurðu = hefur þú
• ertu = ert þú

The meaning is basically the same, but Geturðu is the normal, natural form in everyday Icelandic.

• Geturðu ...? sounds natural and conversational.
• Getur þú ...? is more separated and may sound more careful, emphasized, or formal in some contexts.

For a learner, it is good to recognize both, but Geturðu is the form you will hear a lot.

Because after a modal verb like geta (can), Icelandic often uses the supine form with certain verbs in conversational patterns like this.

Here:

• geturðu sagt mér ... = can you tell me ...

The verb is segja (to say / to tell), and sagt is its supine/participle-type form used in this construction.

This is something learners usually just need to get used to as a fixed pattern:

• Geturðu sagt mér ...? = Can you tell me ...?
• not Geturðu segja mér ...?

So this is an important phrase to memorize as a whole.

Because the verb segja takes an indirect object in the dative case when you are telling something to someone.

• ég = I (nominative)
• mig = me (accusative)
• mér = me / to me (dative)

In this sentence:

• segja mér = tell me / literally say to me

This is very common in Icelandic:

• Hann gaf mér bók. = He gave me a book.
• Geturðu sagt mér ...? = Can you tell me ...?

So mér is there because Icelandic treats the listener as a dative object.

Literally, it is something like:

• hvernig = how
• ég = I
• á að = am supposed to / should / am to
• opna = open

So the whole part means:

• how I am supposed to open
• or more naturally in English: how to open

The expression að eiga að + infinitive is very common and means something like:

• to be supposed to
• should
• be meant to

Examples:

• Ég á að fara. = I am supposed to go.
• Hvað á ég að gera? = What should I do?

Because after hvernig here, you are inside a subordinate clause.

In main questions, Icelandic often has verb-second or inverted word order:

• Hvernig á ég að opna viðhengið? = How am I supposed to open the attachment?

But inside a subordinate clause after sagt mér:

• Geturðu sagt mér hvernig ég á að opna viðhengið ... ?

the subject usually comes before the verb:

• hvernig ég á að opna
• not normally hvernig á ég að opna in this sentence

So this is a classic contrast:

• Direct question: Hvernig á ég að ...?
• Embedded question: ... hvernig ég á að ...

Á að comes from the verb eiga plus að and is a very common construction.

It can mean:

• should
• am supposed to
• am meant to
• sometimes have to, depending on context

In this sentence, it is best understood as:

• how I’m supposed to open the attachment

Other examples:

• Þú átt að læra. = You should study.
• Við eigum að mæta klukkan níu. = We are supposed to arrive at nine.

So á að is not possession here. Even though eiga often means own, in this construction it has a different meaning.

Because opna is an infinitive, and after að in the construction á að + infinitive, Icelandic uses the infinitive form.

So:

• á að opna = is supposed to open / should open

Compare:

• Ég opna viðhengið. = I open the attachment.
  Here opna is a present-tense form.
• Ég á að opna viðhengið. = I am supposed to open the attachment.
  Here opna is the infinitive after að.

In this case, the infinitive happens to look the same as one of the present-tense forms, which can be confusing for learners.

Because Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the.

• viðhengi = attachment
• viðhengið = the attachment

So -ið here is the suffixed definite article.

This is very normal in Icelandic:

• bíll = car

• bíllinn = the car

• hús = house
• húsið = the house

So viðhengið means the attachment, not just an attachment.

Here viðhengið is the direct object of opna, so it is in the accusative.

The noun viðhengi is a neuter noun, and in this form the accusative singular definite looks the same as the nominative singular definite:

• viðhengið

That is why it may not look obviously different.

So in the sentence:

• opna viðhengið = open the attachment

the attachment is the thing being opened, so it is the direct object.

Because the phrase means in the email, and after í meaning in, Icelandic often uses the dative case when talking about location.

• tölvupóstur = email / e-mail
• tölvupóstinum = the email in the dative singular

So:

• í tölvupóstinum = in the email

This has two things happening at once:

1. í requires the dative here because this is a location, not motion.
2. -num includes the definite article, so it means the email, not just an email.

Compare:

• í húsinu = in the house
• í bílnum = in the car
• í tölvupóstinum = in the email

Because Icelandic distinguishes between:

• location = usually dative
• motion toward / into = often accusative

Here the attachment is located in the email, so this is a location idea:

• í tölvupóstinum = in the email → dative

Compare:

• Ég er í bílnum. = I am in the car. → location, dative
• Ég fer í bílinn. = I go into the car. → motion, accusative

So in your sentence, nothing is moving into the email; the attachment is simply in it.

Yes. Icelandic forms compounds very freely, much like German.

• tölva = computer
• póstur = mail/post

Together:

• tölvupóstur = email (literally something like computer mail)

Then Icelandic adds case endings and the definite article to the whole compound:

• tölvupóstur = email
• tölvupóstinn = the email (accusative)
• tölvupóstinum = the email (dative)

So this long-looking word is built very systematically.

Yes, Icelandic has several natural ways to express similar ideas, but Geturðu sagt mér ...? is very common and idiomatic.

For example:

• Geturðu sagt mér hvernig ég á að opna viðhengið í tölvupóstinum?
  = Can you tell me how I’m supposed to open the attachment in the email?

You might also hear:

• Geturðu hjálpað mér að opna viðhengið ...?
  = Can you help me open the attachment ...?

But the original sentence is perfectly natural because it asks for instructions rather than direct physical help.

It is polite and normal, especially in everyday conversation.

• Geturðu sagt mér ...? = friendly, standard Can you tell me ...?

If you wanted to sound a bit softer or more formal, you could use a conditional-style form such as:

• Gætirðu sagt mér ...? = Could you tell me ...?

So:

• Geturðu ...? = Can you ...?
• Gætirðu ...? = Could you ...? (often slightly more polite)

Both are good; the original is completely acceptable.

These are two spots learners often stumble over.

A rough guide:

• Geturðu: the ðu is pronounced with the voiced th sound, like th in this
• viðhengið:
  
  • við has a voiced th sound for ð
  • heng has an h clearly pronounced
  • ið again ends with that voiced th sound plus a short vowel

A very rough English-style approximation might be:

• Geturðu ≈ GEH-tur-thu
• viðhengið ≈ vith-HENG-ith

But Icelandic pronunciation is more precise than that, especially the vowels, so it is best to listen to native audio if possible. The main thing is to notice that ð is not a d sound.

The main clause is:

• Geturðu sagt mér ... ?
  = Can you tell me ... ?

The embedded question is:

• hvernig ég á að opna viðhengið í tölvupóstinum
  = how I am supposed to open the attachment in the email

This is useful to see because Icelandic word order changes between the two.

So structurally, the sentence is:

• [Main clause] Geturðu sagt mér
• [Embedded question] hvernig ég á að opna viðhengið í tölvupóstinum

Recognizing that pattern will help you understand a lot of longer Icelandic sentences.