Gdy doręczenie się opóźni, wybiorę ponowne doręczenie lub zwrot do nadawcy.

Literally, gdy means when. In sentences about the future, though, it can feel very close to English if/when.

So:

• Gdy doręczenie się opóźni... = When/if the delivery is delayed...

Compared with similar words:

• gdy — slightly more formal or written
• kiedy — also when, often more neutral/everyday
• jeśli — more clearly if

In this sentence, gdy sounds natural in formal instructions or system messages.

Because opóźni się comes from the perfective verb opóźnić się.

In Polish, perfective verbs do not normally have a true present tense. Their present-looking forms usually refer to the future.

So:

• opóźnia się = is getting delayed / is delayed / is being delayed
  imperfective, ongoing situation
• opóźni się = will get delayed / ends up delayed
  perfective, one completed event

That is why Gdy doręczenie się opóźni... refers to a future situation.

Here się is part of the verb opóźnić się. It does not mean that something literally delays itself.

In many Polish verbs, się helps create a meaning like:

• become
• happen
• occur
• be done in a non-direct way

So:

• opóźnić coś = to delay something
• opóźnić się = to be delayed / to get delayed

It is best to learn opóźnić się as a whole expression.

Doręczenie is a noun meaning delivery, serving, or handing over to the recipient.

It is common in formal, postal, legal, and administrative language. It can be used for:

• a parcel being delivered
• a letter being delivered
• an official document being served

In everyday speech, people might more often say things like:

• dostawa — delivery
• przesyłka — shipment / parcel
• paczka — package

But doręczenie fits very well in official logistics language.

They can both be translated as delivery, but they are not always interchangeable.

• doręczenie emphasizes the act of getting something to the recipient
• dostawa is broader and often means delivery as a service or supply

Very roughly:

• doręczenie przesyłki = delivery of a shipment to the addressee
• dostawa towaru = delivery of goods

In a postal or courier context, doręczenie sounds especially appropriate.

The two instances have different grammatical roles:

• Gdy doręczenie się opóźni...
  here doręczenie is the subject
• wybiorę ponowne doręczenie...
  here doręczenie is the direct object

But the form stays the same because doręczenie is a neuter singular noun, and in Polish the nominative and accusative are often identical for that type of noun.

So the first doręczenie is nominative, and the second is accusative, even though both look the same.

Wybiorę means I will choose. It is the 1st person singular form of the perfective verb wybrać.

That fits the meaning well because choosing here is seen as:

• one decision
• a completed action
• something done once

Compare:

• wybiorę = I will choose
• będę wybierać = I will be choosing / I will choose repeatedly

In this sentence, wybiorę is the natural choice.

Ponowne means repeat, repeated, or again. So ponowne doręczenie means:

• redelivery
• another delivery attempt
• delivery again

Grammatically, ponowne is an adjective agreeing with doręczenie:

• doręczenie is neuter singular
• so the adjective is also neuter singular: ponowne

Zwrot means return, and do nadawcy means to the sender.

The preposition do takes the genitive case, so:

• nadawca = sender
• nadawcy = of the sender / to the sender after do

So:

• zwrot do nadawcy = return to sender

This is a very common fixed phrase in postal language.

Both lub and albo mean or.

The difference is mainly style:

• lub — a bit more formal, common in writing and official language
• albo — more conversational

Because this sentence sounds like something from a courier or postal interface, lub fits the register very well.

Yes. Polish word order is flexible, although some versions sound more natural than others depending on emphasis and style.

For example, you could also say:

• Gdy się opóźni doręczenie, wybiorę ponowne doręczenie lub zwrot do nadawcy.
• Wybiorę ponowne doręczenie lub zwrot do nadawcy, gdy doręczenie się opóźni.

The original version is perfectly understandable and sounds formal. It places doręczenie early, which keeps the topic clear.

Because the sentence begins with a subordinate clause introduced by gdy:

• Gdy doręczenie się opóźni = subordinate clause
• wybiorę ponowne doręczenie lub zwrot do nadawcy = main clause

In Polish, a subordinate clause is normally separated from the main clause with a comma.

Yes, but it sounds formal and system-like, not casual conversation.

It fits contexts such as:

• courier tracking options
• postal service forms
• automated notifications
• official logistics settings

In everyday speech, a person might say something less formal, for example with paczka, przesyłka, or dostawa. But for a written service message, the original sentence is very natural.