wǒ shōudào xìn le.

收到 means to receive or to get something successfully.

It is made of:

• 收 = to receive, accept, collect
• 到 = to reach, arrive, attain

So 收到 is not just the action of receiving in a general sense; it emphasizes that the result was achieved. In other words, the letter actually arrived in your hands.

Here, 到 is a result complement.

A result complement shows the outcome of an action. In 收到, it shows that the action of 收 reached its intended result.

This pattern is very common in Mandarin:

• 看到 = see successfully / catch sight of
• 听到 = hear
• 找到 = find
• 买到 = manage to buy

So 收到信 means not just receive mail in general, but actually receive the letter.

The 了 here is a sentence-final particle. It signals a new situation or change of state.

So 我收到信了 suggests something like:

• now I have the letter
• the situation has changed
• I wasn’t in the state of having received it before, but now I am

This often overlaps with the idea of completion, but sentence-final 了 is not exactly the same as the English past tense. It is more about the situation being newly true.

Yes, 我收到了信 is also very natural.

A simple way to think about the difference is:

• 我收到了信: focuses more on the completed action
• 我收到信了: focuses more on the new situation now being true

In real conversation, the difference is often small, and both can often be translated as I got the letter or I’ve received the letter.

Very roughly:

• 我收到了信。 = I received the letter.
• 我收到信了。 = I’ve got the letter now.

Not exactly. Mandarin does not match English tense forms one-to-one.

English uses tense and aspect forms like received, have received, and had received. Mandarin usually does not mark time that way. Instead, it often uses:

• context
• time words
• aspect markers
• sentence particles like 了

So 我收到信了 can often be translated as:

• I got the letter
• I’ve received the letter
• The letter has arrived

The best English translation depends on context.

Because Mandarin can use a bare noun as an object when the quantity is not important or is understood from context.

So 信 here can work by itself.

If you want to say one letter explicitly, you would say:

• 我收到一封信了。

Here 封 is the measure word for letters.

Without 一封, the sentence is more neutral and natural when the exact number is not the focus.

It can mean different things depending on context, because Mandarin nouns do not have articles like a or the.

So 信 here could be understood as:

• a letter
• the letter
• sometimes mail in a general sense

Context tells you which one is intended.

For example:

• If you were waiting for one specific letter, 信 will probably mean the letter.
• If someone is just reporting news, it may mean a letter.

Mandarin normally uses Subject–Verb–Object order, just like English in many basic sentences.

So:

• 我 = subject
• 收到 = verb
• 信 = object
• 了 = sentence-final particle

That gives:

• 我 收到 信 了
• I received the letter / I’ve got the letter now

The result complement 到 stays attached to the verb, so 收到 acts as one verb unit.

Yes, if the subject is already clear from context.

In conversation, it is very common to say simply:

• 收到信了。

That can still mean I got the letter, as long as it is obvious who is speaking about themselves.

Mandarin often drops subjects when they are understood.

Here 了 is pronounced le with a neutral tone.

So the sentence is:

• wǒ shōudào xìn le

A few pronunciation notes:

• 我 wǒ = 3rd tone
• 收 shōu = 1st tone
• 到 dào = 4th tone
• 信 xìn = 4th tone
• 了 le = neutral tone, light and short

The final le should not sound heavy or stressed.