Recebe o correio registado, contanto que leve o documento.

It can be understood in two ways, because recebe has the same form in both:

• 3rd person singular present indicative: he/she receives
• imperative for tu: receive

In an isolated sentence like this, the form is ambiguous. Context normally tells you which one is meant.

If this is an instruction to someone, it is probably:

• Recebe o correio registado... = Receive the registered mail...

If it is a statement about someone, it is probably:

• Ele/Ela recebe o correio registado... = He/She receives the registered mail...

In European Portuguese, leaving out the subject pronoun is very common, so both readings are possible without more context.

Portuguese often omits subject pronouns when the verb form already gives enough information.

So instead of saying:

• Tu recebes...
• Ele recebe...
• Ela recebe...

Portuguese often just says:

• Recebes...
• Recebe...

In this sentence, the omitted subject is one reason the beginning sounds ambiguous. Portuguese is much more comfortable than English with leaving the subject unstated.

Correio registado means registered mail.

Here:

• correio = mail, post
• registado = registered

So correio registado refers to post that is officially registered and usually requires more formal handling, tracking, or signature.

In real-life usage, Portuguese may also use more specific expressions depending on the item:

• carta registada = registered letter
• encomenda registada = registered parcel/package

But correio registado is understandable as a general expression for registered mail.

Portuguese uses definite articles much more often than English.

So where English may say:

• registered mail

Portuguese often says:

• o correio registado

The article o can sound natural even when English would use no article at all.

It can suggest:

• the registered mail
• or simply the mail in question, already understood from the situation

This is a very common difference between English and Portuguese.

Contanto que means provided that, as long as, or on condition that.

It introduces a condition:

• Recebe o correio registado, contanto que leve o documento.
• Receive the registered mail, provided that you bring the document.

It is correct, but in everyday European Portuguese, learners will often hear:

• desde que
• se

For example:

• Recebe o correio registado, desde que leve o documento.

So contanto que is perfectly valid, but it can sound a bit more formal or literary than some other options.

Because contanto que normally requires the subjunctive.

So:

• contanto que leve
• not contanto que leva

This is because the clause expresses a condition, not a simple fact.

The verb levar in the present subjunctive is:

• eu leve
• tu leves
• ele/ela/você leve
• nós levemos
• vós leveis
• eles/elas/vocês levem

So leve here is the correct subjunctive form.

Usually, yes, that is the most natural reading.

The sentence normally implies that the person receiving the registered mail must bring the document.

Because Portuguese often omits pronouns, the clause does not explicitly name the subject. So depending on context, leve could refer to:

• he/she
• you in the formal sense (você)
• sometimes even I, because eu leve has the same form

But in normal usage, listeners usually assume the same person is involved unless context suggests otherwise.

That is a very good question, because English often uses bring where Portuguese chooses either levar or trazer depending on perspective.

Very roughly:

• levar = to take
• trazer = to bring

But in real Portuguese usage, the choice depends on the speaker’s point of view.

In this sentence, leve o documento suggests take/carry the document with you. It focuses on the person having the document when they go to receive the mail.

A speaker could also say traga o documento in some contexts, especially if thinking from the point of view of the place where the document must be presented. But leve o documento is still quite natural if the idea is make sure you have the document with you.

Leve is the present subjunctive form of levar.

It can correspond to several subjects:

• eu leve
• ele leve
• ela leve
• você leve

That is why, by itself, leve does not tell you exactly who the subject is.

This kind of overlap is very common in Portuguese verb forms, so context is important.

The comma separates the main clause from the conditional subordinate clause.

Main clause:

• Recebe o correio registado

Subordinate clause:

• contanto que leve o documento

This comma is natural and helps mark the condition clearly. You may see punctuation vary a little depending on style, but with a connector like contanto que, the comma is very normal.

Yes. In many situations, desde que is a very natural alternative.

For example:

• Recebe o correio registado, desde que leve o documento.

This still means provided that or as long as.

Like contanto que, desde que also normally takes the subjunctive:

• desde que leve

For many learners, desde que is worth learning early because it is very common in both spoken and written Portuguese.

It is grammatical and understandable, but a native speaker might choose a slightly different wording depending on the situation.

Possible alternatives include:

• Recebe o correio registado, desde que leve o documento.
• Só recebe o correio registado se levar o documento.
• Pode receber o correio registado, desde que leve o documento.

These can sound a bit more explicit or natural in everyday use, especially:

• Só recebe... se levar...
• Pode receber... desde que leve...

The original sentence is fine, but in real conversation many speakers might prefer one of those versions.