Trước khi gửi email, tôi luôn kiểm tra lại rất cẩn thận.

Trước khi means before in the sense of before doing something.

In this sentence, Trước khi gửi email means Before sending an email.

A useful pattern is:

trước khi + verb phrase

Examples:

• Trước khi ăn, tôi rửa tay. = Before eating, I wash my hands.
• Trước khi đi ngủ, cô ấy đọc sách. = Before going to bed, she reads books.

So here, trước khi introduces the action that happens first: gửi email.

Vietnamese often omits a subject when it is already clear from context.

In Trước khi gửi email, tôi luôn kiểm tra lại rất cẩn thận, the subject of gửi email is understood to be the same as tôi later in the sentence.

So the full logical meaning is: Before I send email, I always check again very carefully.

You could make the subject explicit in some contexts, but it is usually unnecessary and less natural here.

Vietnamese commonly uses email directly, especially in everyday modern speech and writing. It is a borrowed word and is completely normal.

You may also see:

• thư điện tử = electronic mail, more formal or official
• email = much more common in daily use

So gửi email is the natural everyday way to say send an email.

Luôn means always.

It shows habitual or consistent behavior. In this sentence:

tôi luôn kiểm tra lại rất cẩn thận = I always check again very carefully

Vietnamese adverbs like luôn often come before the main verb, so:

• tôi luôn kiểm tra... not usually
• tôi kiểm tra luôn... in this meaning

Kiểm tra means to check.

Kiểm tra lại means to check again, to re-check, or often very naturally in English, to double-check.

The word lại often adds the idea of doing something another time or again.

So:

• kiểm tra = check
• kiểm tra lại = check again / double-check

In this sentence, lại is important because it suggests the speaker is not just checking once, but reviewing the email again before sending it.

Not always. Lại is a very common Vietnamese word with several uses depending on context.

In this sentence, it means again.

But in other contexts, lại can also suggest things like:

• repetition: làm lại = do again
• return: quay lại = come back / turn back
• contrast or surprise in some structures

So you should learn lại by pattern and context rather than trying to force one single English translation every time.

In Vietnamese, manner expressions often come after the verb.

So:

• kiểm tra lại rất cẩn thận = check again very carefully

This is a normal Vietnamese word order: verb + adverbial description

Here:

• kiểm tra lại = check again
• rất cẩn thận = very carefully

Even though cẩn thận is basically an adjective meaning careful, Vietnamese often uses adjectives after verbs in a way that English translates as adverbs.

Formally, cẩn thận is usually treated as an adjective meaning careful.

But after a verb, it can function like an adverb in English:

• làm cẩn thận = do something carefully
• nói cẩn thận = speak carefully
• kiểm tra cẩn thận = check carefully

So in this sentence, although cẩn thận is adjective-like in Vietnamese, the natural English translation is adverbial: carefully.

Rất means very.

It intensifies cẩn thận:

• cẩn thận = careful / carefully
• rất cẩn thận = very careful / very carefully

So: kiểm tra lại rất cẩn thận = check again very carefully

This is one of the most common Vietnamese patterns: rất + adjective

The comma separates the introductory time clause from the main clause.

So the sentence has two parts:

• Trước khi gửi email = before sending email
• tôi luôn kiểm tra lại rất cẩn thận = I always double-check very carefully

The comma helps readability, just like in English: Before sending an email, I always check it very carefully.

In casual writing, people are not always strict with commas, but this comma is correct and helpful.

Yes, it can, although the original version is very natural.

For example: Tôi luôn kiểm tra lại rất cẩn thận trước khi gửi email.

This also means: I always double-check very carefully before sending an email.

Both word orders are natural:

• Trước khi gửi email, tôi luôn...
• Tôi luôn... trước khi gửi email.

The first version puts a little more focus on the time frame before sending the email.

Vietnamese often omits pronouns when the subject is obvious, but including tôi is very normal and natural.

Here, tôi makes the sentence clear and complete: tôi luôn kiểm tra lại rất cẩn thận

If the context already made the subject obvious, a speaker might omit it in conversation, but in a standalone sentence, tôi is the most natural choice.

So:

• Tôi luôn kiểm tra lại rất cẩn thận. = clear, standard
• Omitting tôi would depend more on context

Vietnamese nouns usually do not mark singular vs. plural the way English does.

So gửi email could mean:

• send an email
• send emails

The exact number depends on context.

In this sentence, English would often translate it as Before sending an email... because that sounds natural as a general habit statement. But Before sending emails... could also fit in the right context.

Yes.

Compare them:

• kiểm tra cẩn thận = check carefully
• kiểm tra lại cẩn thận = check again carefully
• kiểm tra lại rất cẩn thận = check again very carefully

Adding lại and rất makes the sentence stronger and more specific. It suggests a deliberate habit of reviewing the email thoroughly before sending it.

A very natural understanding is:

Before sending an email, I always double-check it very carefully.

That is slightly freer than a word-for-word translation, but it captures the grammar and the meaning well:

• trước khi = before
• gửi email = sending an email
• luôn = always
• kiểm tra lại = check again / double-check
• rất cẩn thận = very carefully

So double-check is often the best natural English equivalent for kiểm tra lại in this context.