huutou no sasidasinin no namae wo mireba, dare kara no tegami ka sugu wakarimasu.

No. Standard Japanese is usually written without spaces:

封筒の差出人の名前を見れば、だれからの手紙かすぐ分かります。

The spaces here are just a learning aid to show where the parts of the sentence are.

見れば is the -eba conditional form of 見る.

• Dictionary form: 見る = to see / to look at
• Conditional: 見れば = if you look / when you look

So 名前を見れば means if you look at the name or when you look at the name.

In this sentence, it sets up the condition for the result:

• 見れば → if you look
• 分かります → you will understand / you can tell

Yes, 見たら would also be natural:

封筒の差出人の名前を見たら、だれからの手紙かすぐ分かります。

The difference is small here, but there is a nuance:

• 見れば sounds a bit more like a general condition: if you look
• 見たら often sounds more like when/after you look

In everyday speech, both are very common. In this sentence, either works.

The particle の links nouns together.

Here the chain is:

• 封筒 = envelope
• 差出人 = sender
• 名前 = name

So:

• 封筒の差出人 = the sender on the envelope
• 差出人の名前 = the sender’s name
• 封筒の差出人の名前 = the sender’s name on the envelope

Japanese often stacks nouns this way. It can feel long in English, but it is very normal in Japanese.

差出人 means sender or the person who sent something.

In the context of a letter or envelope, it means the person the letter is from. On an envelope, it is basically the sender / return sender information.

So 封筒の差出人の名前 means the name of the sender written on the envelope.

Because 名前 is the direct object of 見る.

• 名前を見れば = if you look at the name

The verb 見る normally takes を for the thing being looked at. Even though the verb is in the conditional form 見れば, it still keeps its normal object marker.

This is a very important structure.

Break it down like this:

• だれ = who
• から = from
• だれから = from whom
• だれからの手紙 = a letter from whom
• だれからの手紙か = who the letter is from

The か here marks an embedded question or indirect question. It is not a direct question by itself. It is part of what is being understood.

So the whole sentence means something like:

• If you look at the sender’s name on the envelope, you can immediately tell who the letter is from.

Because 分かる means to understand, to become clear, or to be able to tell.

Here, the idea is not I learn it as new information in the sense of 知る. The idea is:

• by looking at the name,
• the answer becomes clear,
• so you can tell who sent the letter.

That is exactly the kind of situation where Japanese prefers 分かる.

So:

• 分かります = you understand / you can tell / it becomes clear
• 知ります = to get to know / to learn / to find out

In this sentence, 分かります is the natural choice.

すぐ means immediately, right away, or quickly.

So:

• すぐ分かります = you can tell right away

It emphasizes that once you look at the sender’s name, the answer is obvious immediately.

The subject is omitted, which is very common in Japanese.

Depending on context, it could mean:

• you can tell
• one can tell
• we can tell

Japanese often leaves out subjects when they are obvious or unimportant. Here the sentence is making a general statement, so English might naturally translate it with you or you can.

Not exactly.

• だれからの手紙 = a letter from whom
• だれの手紙 = whose letter

In many contexts, they can point to the same real-world meaning, but だれからの手紙 is more explicit about the sender. Since this sentence is about the 差出人, using だれからの手紙 fits very well.