Vou responder ao e-mail da empresa amanhã de manhã.

In Brazilian Portuguese, the construction ir + infinitive is very common for talking about the future.

• vou responder = I am going to reply / I will reply
• vou is the present tense of ir for eu
• responder stays in the infinitive

There is also a simple future form:

• responderei ao e-mail da empresa amanhã de manhã

That is correct, but in everyday speech vou responder sounds much more natural and common.

Portuguese often drops subject pronouns when the verb already makes the subject clear.

• vou already tells you the subject is eu = I
• So (Eu) vou responder... and Vou responder... both mean the same thing

Portuguese does this much more than English. The pronoun can be included for emphasis, contrast, or clarity, but it is not necessary here.

Because the verb responder normally takes the preposition a when you respond to something or someone.

So:

• responder a algo
• responder a alguém

That is why:

• ao e-mail = a + o e-mail

English says reply the email in some contexts, but Portuguese usually uses the equivalent of reply to the email.

Examples:

• Respondi ao professor. = I replied to the teacher.
• Ela respondeu à mensagem. = She replied to the message.

Ao is a contraction of:

• a
  • o = ao

Here:

• a is the preposition required by responder
• o is the masculine singular definite article the

So:

• ao e-mail = to the email

Portuguese uses these contractions very often, and they are important to learn.

Other common ones:

• a + a = à
• de + o = do
• de + a = da
• em + o = no
• em + a = na

Yes, e-mail comes from English, but in Portuguese it behaves like a normal noun and usually takes an article.

So you will often see:

• o e-mail = the email
• um e-mail = an email

In Brazilian Portuguese, people also say email without the hyphen, and in more formal or official language you may also see correio eletrônico, though that is less common in everyday conversation.

Da is the contraction of:

• de
  • a = da

So:

• o e-mail da empresa = the company’s email / the email from the company

This structure is very common in Portuguese for possession or association.

Examples:

• o carro do meu irmão = my brother’s car
• a gerente da loja = the manager of the store

In this sentence, it most naturally means the email from the company or the company email/message that the speaker plans to reply to.

If you wanted to be very clear that you mean an email address, Portuguese would more likely say:

• o endereço de e-mail da empresa

So in this sentence, e-mail is best understood as the message itself.

It may sound repetitive to an English speaker because both parts relate to time, but this is a very normal Portuguese expression.

• amanhã = tomorrow
• de manhã = in the morning

Together:

• amanhã de manhã = tomorrow morning

This is one of the most common ways to say it in Brazilian Portuguese.

Similar expressions:

• hoje de manhã = this morning
• amanhã à tarde = tomorrow afternoon
• amanhã à noite = tomorrow night

That is just the standard pattern in Portuguese:

• de manhã = in the morning
• à tarde = in the afternoon
• à noite = at night / in the evening

This is something learners usually just need to memorize as a set of common time expressions.

Examples:

• Trabalho de manhã. = I work in the morning.
• Estudo à tarde. = I study in the afternoon.
• Saio à noite. = I go out at night.

Yes. Portuguese is fairly flexible with time expressions.

The original sentence:

• Vou responder ao e-mail da empresa amanhã de manhã.

This is very natural.

You could also say:

• Amanhã de manhã, vou responder ao e-mail da empresa.
• Vou amanhã de manhã responder ao e-mail da empresa. (possible, but less neutral in everyday use)

The most natural choices are usually:

• time expression at the end
• or time expression at the beginning for emphasis

A more formal version could be:

• Responderei ao e-mail da empresa amanhã de manhã.

This uses the simple future responderei instead of vou responder.

Both are correct, but:

• vou responder = more common and conversational
• responderei = more formal, more written, or sometimes more deliberate

In Brazil, e-mail is usually pronounced approximately like i-meiu.

It sounds adapted to Portuguese pronunciation rather than exactly like English email.

You may also hear:

• email written without the hyphen
• the pronunciation staying roughly the same

No, not in standard Portuguese for this meaning.

The normal pattern is:

• responder a alguém / a alguma coisa

So:

• Vou responder ao e-mail. = correct

But:

• Vou responder para o e-mail. = not natural here

If you want to make the action more explicit, you could say:

• Vou dar resposta ao e-mail. (more formal / less common in everyday speech)
• Vou responder a esse e-mail. = I’m going to reply to that email

Yes, but it changes the rhythm and emphasis.

For example:

• Vou responder amanhã de manhã ao e-mail da empresa.

This is grammatically correct, but many speakers may prefer the original version because it flows more naturally:

• Vou responder ao e-mail da empresa amanhã de manhã.

In everyday speech, Portuguese often places the object first and the time expression afterward, especially in simple neutral statements.