Даже если курьер позвонит поздно, я всё равно попрошу его оставить коробку у двери, а потом спокойно напишу отзыв.

Даже если means even if, not just if.

• если = if
• даже если = even if

So the speaker is saying that the rest of the plan will happen regardless of that condition. It adds a stronger sense of “that won’t change what I do.”

Compare:

• Если курьер позвонит поздно... = If the courier calls late...
• Даже если курьер позвонит поздно... = Even if the courier calls late...

That fits well with всё равно later in the sentence.

Позвонит is the perfective future of позвонить, meaning will call / will make a call as a single completed action.

Russian often chooses aspect based on how the action is viewed:

• позвонит = one completed call
• будет звонить = will be calling / will call repeatedly or over a period
• звонит = is calling / calls

Here, the courier is expected to make one call, so позвонит is the natural choice.

This is a very common difference between English and Russian.

In Russian, after если, you normally use the tense that matches the real time of the action:

• present for present/general conditions
• future for future conditions

So for a future situation, Russian says:

• Если он позвонит, я отвечу. = If he calls, I’ll answer.

Even though English uses a present form after if, Russian uses a future form here. So если курьер позвонит поздно is completely normal.

Всё равно means anyway, all the same, or regardless.

In this sentence, it reinforces the idea already introduced by даже если:

• Даже если ... , я всё равно ...
• Even if ... , I’ll still ...

So the speaker means: even if the courier calls late, I will still ask him to leave the box at the door.

This is a very common pattern in Russian:

• Даже если будет дождь, мы всё равно пойдём. = Even if it rains, we’ll still go.

This is the standard Russian construction for ask someone to do something:

• попросить кого-то + infinitive

So:

• попрошу его оставить коробку
  = I’ll ask him to leave the box

Here:

• его = him (the person being asked)
• оставить = to leave

Russian does not need a word like English to before him. The structure is simply:

• Я попрошу курьера подождать.
• Она попросила меня помочь.

Оставить is perfective, so it presents the action as a single completed result: the box ends up left at the door.

That fits this sentence well, because the speaker wants one concrete outcome:

• the courier leaves the box
• the action is completed

If you used оставлять, it would sound more like a repeated, habitual, or process-oriented action, which does not fit as well here.

So:

• оставить коробку у двери = leave the box at the door as one completed act

Because коробку is the accusative case, used here for the direct object of оставить.

The courier is leaving what?

• коробку

So:

• nominative: коробка
• accusative: коробку

This is a regular pattern for feminine nouns ending in -а:

• машина → машину
• книга → книгу
• дверь is different, because it follows a different declension pattern.

У двери means by the door / at the door.

The preposition у normally takes the genitive case, so:

• дверь → двери

So:

• у двери = by the door
• у дома = by the house
• у окна = by the window

This is a very common location phrase in Russian.

They mean different things:

• у двери = by the door / at the door → location
• к двери = toward the door → direction

In this sentence, the box is supposed to be left next to the door, so the location phrase у двери is correct.

Compare:

• Поставь коробку у двери.
  = Put the box by the door.
• Подойди к двери.
  = Go up to the door.

Отзыв means review, feedback, or written opinion, depending on context.

In this sentence, it most naturally means a review, probably about the delivery service or courier.

The verb написать is very natural with отзыв:

• написать отзыв = write a review

This is a common collocation. It can refer to:

• an online review
• customer feedback
• a written comment

The exact meaning depends on the situation, but review/feedback is the right idea here.

Напишу is the perfective future of написать, and it focuses on the completed result: the review will get written.

That works well here because the sentence presents a sequence of completed actions:

1. I’ll ask him to leave the box
2. then I’ll write a review

If you said буду писать, it would emphasize the process of writing rather than the finished result. That is less natural here.

So:

• напишу отзыв = I’ll write a review / I’ll get the review written
• буду писать отзыв = I’ll be writing a review

Спокойно literally means calmly, peacefully, or without stress.

In this sentence, it suggests something like:

• without getting upset
• without rushing
• in a calm way

So а потом спокойно напишу отзыв implies the speaker will deal with the situation calmly and then write the review.

It adds tone, not just factual information.

Both can sometimes be translated as and then, but а often marks a transition or a slight contrast between steps, while и more simply links actions.

Here, а потом sounds natural because the speaker moves from one action to the next:

• first: ask the courier to leave the box
• then: write a review

So а потом can feel like:

• and then after that
• and after that

It is not a strong contrast, but it helps organize the sequence smoothly.

Russian word order is fairly flexible, but the chosen order sounds natural and highlights the intended meaning.

This sentence:

• Даже если курьер позвонит поздно, я всё равно попрошу его оставить коробку у двери, а потом спокойно напишу отзыв.

has a very natural flow:

1. condition
2. main action
3. next action

You can move some elements for emphasis, but the meaning or tone may shift. For example:

• Я всё равно попрошу его оставить коробку у двери...
  puts stronger focus on what I’ll do anyway
• Спокойно напишу отзыв
  gives a bit more emphasis to calmly

So the word order is not totally fixed, but the original version is clear and idiomatic.