Ti allego il documento, così puoi controllarlo subito.

Ti is the indirect object pronoun meaning to you.

So Ti allego il documento literally works like:

• allego = I attach
• ti = to you
• il documento = the document

A natural English rendering is I’m attaching the document for you / I’m attaching the document to this message.

In Italian, allegare often works with:

• the thing attached = direct object
• the person receiving it = indirect object

So:

• Ti allego il documento. = I’m attaching the document for you / sending you the attached document.

You could also hear:

• Le allego il documento. = formal I’m attaching the document for you
• Vi allego il documento. = I’m attaching the document for you all

Italian often leaves out subject pronouns when they are already clear from the verb ending.

Here, allego already means I attach, so io is not necessary.

• (Io) allego = I attach
• (Tu) alleghi = you attach
• (Lui/lei) allega = he/she attaches

So Ti allego il documento is perfectly normal Italian.
Adding io would usually give extra emphasis, like:

• Io ti allego il documento = I’m the one attaching the document

Italian uses articles more often than English does.

Here il documento means the document, referring to a specific document that both speaker and listener can identify from the context.

In English, we often say:

• I’m attaching the document or even
• I’m attaching a document

But in Italian, if it is a specific file already understood in the conversation, il documento is the normal choice.

So:

• Ti allego il documento sounds natural
• Ti allego documento is incorrect

In this sentence, così means something like:

• so
• so that
• that way

It connects the two parts of the sentence:

• Ti allego il documento
• così puoi controllarlo subito

So the idea is:
I’m attaching the document, so you can check it right away.

This use of così is very common in everyday Italian when introducing a practical result or purpose.

Similar examples:

• Te lo scrivo, così non lo dimentichi.
  I’ll write it down for you, so you don’t forget it.
• Partiamo presto, così arriviamo in tempo.
  Let’s leave early, so we arrive on time.

The -lo refers back to il documento.

• controllare = to check
• lo = it (masculine singular, referring to il documento)
• controllarlo = to check it

So instead of repeating il documento, Italian replaces it with the pronoun lo:

• puoi controllare il documento
• puoi controllarlo

Both mean:

• you can check the document
• you can check it

Because documento is masculine singular, the pronoun is lo.
If it were feminine, it would be la:

• la lettera → controllarla = to check it

Yes. After modal verbs like:

• potere = can
• dovere = must
• volere = want

the object pronoun can often go in two places:

1. before the conjugated verb
2. attached to the infinitive

So both of these are correct:

• Lo puoi controllare.
• Puoi controllarlo.

Both mean You can check it.

In your sentence, puoi controllarlo sounds very natural.

What you cannot say is:

• puoi lo controllare ❌

So with a modal verb, the pronoun goes either:

• before the modal: lo puoi controllare
• attached to the infinitive: puoi controllarlo

No — and this is an important false friend for English speakers.

In Italian, controllare often means:

• to check
• to inspect
• to verify

So here controllarlo means to check it, not to control it.

Depending on context, controllare can sometimes mean to control in the sense of to monitor or to keep under control, but in office/email contexts it very often means check.

Examples:

• Controlla l’email. = Check the email.
• Devo controllare i dati. = I need to check the data.

So in this sentence, think check, not control.

Subito means:

• immediately
• right away
• straight away

In this sentence, it adds the idea that the person can check the document without delay:

• così puoi controllarlo subito = so you can check it right away

It is a very common adverb in Italian.

Examples:

• Arrivo subito. = I’ll be there right away.
• Te lo mando subito. = I’ll send it to you immediately.

Yes, the comma is natural and helpful here because it separates the two clauses:

• Ti allego il documento
• così puoi controllarlo subito

It reflects the pause you would normally make in speech and makes the sentence easier to read.

In informal writing, punctuation can vary, but with this structure the comma is standard and recommended.

It is informal or neutral, mainly because of ti, which means to you in the familiar singular form.

So this is appropriate when writing to:

• a colleague you are on familiar terms with
• a friend
• someone you address with tu

If you want a formal version, you would usually say:

• Le allego il documento, così può controllarlo subito.

Here:

• Le = formal to you
• può = formal you can

So the choice between ti and Le depends on the relationship and level of formality.

Yes, but the meaning is slightly different.

• Ti allego il documento specifically means I’m attaching the document (for example, to an email).
• Ti mando il documento means I’m sending you the document, which is more general.

So if you want to emphasize that the file is an attachment, allego is the better verb.

Compare:

• Ti allego il documento. = I’m attaching the document.
• Ti mando il documento. = I’m sending you the document.

In email or business communication, allegare is especially common because it refers directly to an attachment.