Você pode me mandar o link de novo? Acho que abri o site errado e baixei o anexo antigo.

Both are possible, but in Brazilian Portuguese, me mandar is much more natural in everyday speech.

• Você pode me mandar o link...? = the most common spoken order
• Você pode mandar-me o link...? = grammatically possible, but sounds more formal or more European Portuguese-like

In Brazil, object pronouns like me, te, lhe usually come before the verb in normal speech.

Yes, here de novo means again.

So:

• mandar o link de novo = send the link again

De novo and novamente can both mean again, but:

• de novo is more common in everyday conversation
• novamente sounds a bit more formal or written

In this sentence, de novo is the most natural choice.

In Portuguese, borrowed nouns usually get assigned a grammatical gender, and link is normally treated as masculine in Brazilian Portuguese.

So people say:

• o link
• um link
• esse link

There is not always a deep logical reason for the gender of borrowed words; it is often just how the language settled on using them.

Both can mean to send, but they feel slightly different:

• mandar = very common, informal, conversational
• enviar = also common, but a bit more neutral or formal

So:

• Você pode me mandar o link? = very natural in speech
• Você pode me enviar o link? = also correct, slightly more formal

In casual Brazilian Portuguese, mandar is extremely common for sending links, files, messages, and so on.

Because achar que + clause is the normal structure for I think that...

• Acho que abri o site errado = I think I opened the wrong site

You do not say acho de que here.

The verb achar can work in different ways:

• Acho isso estranho. = I find this strange.
• Acho que ele vem. = I think he is coming.

In your sentence, it introduces a full idea, so achar que is the correct pattern.

Abri is the first-person singular preterite of abrir.

• abrir = to open
• abri = I opened

The preterite is used for a completed action in the past. Here, the speaker means they already opened the site.

So:

• Acho que abri o site errado = I think I opened the wrong site

It sounds like a single completed action, which is why the preterite fits well.

In Portuguese, adjectives usually come after the noun.

• o site errado = the wrong site
• o anexo antigo = the old attachment

That is the normal word order.

Sometimes adjectives can come before the noun, but that often changes the style or nuance. For a basic descriptive meaning like this, noun + adjective is the usual pattern.

It can mean both, depending on context.

Here, o site errado means:

• the wrong site
• the incorrect site
• not the site I meant to open

So it is not about morality here. It is simply the mistaken one.

Baixei is the preterite of baixar, and in technology contexts it very often means I downloaded.

So:

• baixei o anexo antigo = I downloaded the old attachment

But baixar has other meanings too, such as:

• baixar o volume = lower the volume
• baixar a cabeça = lower one’s head

So the exact meaning depends on context. In this sentence, because of site and anexo, it clearly means downloaded.

Yes. In this context, anexo means attachment.

• baixei o anexo antigo = I downloaded the old attachment

In Brazilian Portuguese, anexo is commonly used for files attached to emails, forms, messages, or websites.

You may also hear:

• arquivo anexado = attached file
• o anexo do e-mail = the email attachment

Good question, because antigo can mean different things.

It can mean:

• old in age
• former / previous / earlier

In this sentence, o anexo antigo most likely means:

• the old attachment
• the earlier/previous attachment
• not the updated one

So the idea is probably I downloaded the older version / previous attachment, not necessarily something physically old.

Because Portuguese often omits subject pronouns when the verb ending already makes the subject clear.

• abri already means I opened
• baixei already means I downloaded

So eu is not necessary.

You could say:

• Acho que eu abri o site errado e baixei o anexo antigo

But leaving out eu is very common and natural.

Because the speaker is simply linking two actions:

• opened the wrong site
• downloaded the old attachment

So e = and is enough.

• abri o site errado e baixei o anexo antigo

If the speaker wanted to emphasize consequence more strongly, they could say something else, but e sounds natural and efficient here. In conversation, Portuguese often uses simple coordination where English might also use and.

Yes, that is understandable and correct, but it sounds a bit more formal or less conversational.

Compare them:

• Você pode me mandar o link de novo? Acho que abri o site errado e baixei o anexo antigo.

  • very natural, everyday Brazilian Portuguese

• Você pode me enviar o link novamente? Acho que eu entrei no site errado e fiz download do anexo antigo.

  • correct, but slightly more formal or technical

A few nuances:

• mandar is more casual than enviar
• de novo is more conversational than novamente
• baixei is usually more natural than fiz download in everyday speech
• abri o site means opened the site, while entrei no site means went onto / entered the site; both can work, but they are slightly different actions

Yes, it is already polite enough for many everyday situations because it uses Você pode...? rather than a direct command.

• Você pode me mandar o link de novo? = polite and natural

If you want to sound even softer, you could add:

• por favor
• quando puder
• será que você pode...?

For example:

• Você pode me mandar o link de novo, por favor?
• Quando puder, você pode me mandar o link de novo?
• Será que você pode me mandar o link de novo?

These make the request sound even gentler.