De haber enviado la mercancía, habrían reembolsado el importe.

Here, de haber enviado means if someone had sent.

It is a fairly formal, condensed way to express a past unreal condition. In full, the idea is:

• De haber enviado la mercancía...
• = Si hubieran enviado la mercancía...
• = If they had sent the goods...

So the whole sentence means something like:

• Had they sent the goods, they would have refunded the amount
• or more naturally in English, If they had sent the goods, they would have refunded the amount

Because Spanish can sometimes omit si in formal conditional expressions.

The pattern here is:

• de + haber + past participle

This works like a reduced version of an if clause. So:

• Si hubieran enviado la mercancía, habrían reembolsado el importe
• De haber enviado la mercancía, habrían reembolsado el importe

Both express the same basic idea.

For learners, the easiest way to think about it is:

• si hubieran enviado... = the more straightforward textbook version
• de haber enviado... = a more formal, compressed alternative

Because the sentence refers to an action that would have happened before the refund.

• enviar = to send
• haber enviado = to have sent

The perfect infinitive haber + past participle shows that the sending would already have been completed.

So:

• De enviar la mercancía... would not mean the same thing.
• De haber enviado la mercancía... specifically means if they had sent the goods.

This matches the second half:

• habrían reembolsado = they would have refunded

Both halves refer to an unreal situation in the past.

Habrían reembolsado is the conditional perfect.

It is formed with:

• haber in the conditional: habría, habrías, habría, habríamos, habríais, habrían
• • past participle: reembolsado

So:

• habrían reembolsado = they would have refunded

This tense is commonly used for:

• hypothetical actions in the past
• actions that would have happened if a condition had been met

That is exactly what is happening here.

Spanish often leaves the subject unstated when it is understood from context.

So habrían reembolsado could mean:

• they would have refunded
• you all would have refunded
• in some contexts, another implied subject

Likewise, the subject of haber enviado is also not stated.

In real life, context would usually make it clear who is meant. For example:

• the customer might be the one who should have sent the goods
• the company might be the one that would have refunded the amount

If you want to make it clearer, Spanish can add pronouns or nouns:

• De haber enviado usted la mercancía, le habrían reembolsado el importe.
• If you had sent the goods, they would have refunded the amount to you.

So the original sentence is grammatically fine, but it is somewhat context-dependent.

Because after haber, the past participle does not agree with the noun.

So you say:

• haber enviado la mercancía
• not haber enviada la mercancía

This is the same rule as in other compound forms:

• He enviado la carta
• Habían enviado los paquetes
• Habrían enviado la mercancía

The participle stays in its default form:

• enviado
• reembolsado

Agreement is a different issue, seen with forms used adjectivally, for example:

• la mercancía enviada
• las cartas enviadas

But that is not what is happening here.

El importe means the amount, usually the amount of money involved in a payment, invoice, refund, or charge.

In commercial or administrative language, it is very common. It sounds more formal and precise than simply saying:

• el dinero
• the money

So in this sentence:

• reembolsar el importe = to refund the amount

Related words:

• el precio = the price
• el coste / costo = the cost
• el importe = the monetary amount, especially in billing/refund contexts

In Spain, importe is very normal in formal or business Spanish.

Because Spanish uses the definite article more often than English does.

Here, both nouns refer to something specific and understood in context:

• la mercancía = the goods / the merchandise in question
• el importe = the amount in question

English might sometimes omit or vary the article depending on style, but Spanish very naturally keeps it.

This is especially common in business or administrative language, where the speaker refers to known items in a transaction.

Often, yes, if you want to show to whom the refund would have been made.

The sentence as given is grammatical, but it does not explicitly say who would receive the refund. In context, that may already be obvious.

A more explicit version would be:

• De haber enviado la mercancía, le habrían reembolsado el importe.
• If you had sent the goods, they would have refunded the amount to you.

Or:

• De haber enviado la mercancía, les habrían reembolsado el importe.
• If they had sent the goods, they would have refunded the amount to them.

So the original sentence is fine, but it is a bit stripped down. Spanish often omits information that the listener is expected to infer from context.

It is natural, but it sounds formal and somewhat written or administrative.

Two things contribute to that tone:

• de haber enviado instead of si hubieran enviado
• reembolsado el importe, which is business-style vocabulary

In everyday conversation, many speakers would more likely say:

• Si hubieran enviado la mercancía, les habrían devuelto el dinero.

That version is less formal and more conversational.

So the original sentence is perfectly good Spanish, especially in:

• customer service messages
• legal or commercial writing
• formal explanations

Yes. That is the most direct equivalent, and for many learners it is the easiest version to understand.

Compare:

• De haber enviado la mercancía, habrían reembolsado el importe.
• Si hubieran enviado la mercancía, habrían reembolsado el importe.

The meaning is basically the same.

If you are still getting used to this structure, it is a good idea to mentally convert de haber + participle into si + pluperfect subjunctive:

• de haber enviado → si hubieran enviado

That will help you recognise the pattern quickly when reading formal Spanish.