orei no messeezi wo okurimasita.

お礼 means thanks, gratitude, or an expression of appreciation.

In this sentence, it does not mean a physical reward or return gift. It means the act of thanking someone, so お礼のメッセージ is a message expressing thanks.

Also, お礼 is a very common and natural word in Japanese. You will often see it in phrases like:

• お礼を言う = to say thank you
• お礼のメール = a thank-you email
• お礼をする = to express thanks / do something in thanks

The particle の is linking two nouns.

Here, お礼のメッセージ literally means something like:

• a message of thanks
• a thank-you message

A very common beginner way to think about A の B is:

• B related to A
• B of A
• A-type B

So here:

• お礼 = thanks
• メッセージ = message
• お礼のメッセージ = a message related to thanks

It is not always a literal English of. It is just a very flexible noun-linking pattern.

メッセージ is a loanword from English message, written in katakana.

Japanese uses many loanwords, and メッセージ is very normal. In context, it can mean:

• a written message
• a text or app message
• a general message sent to someone

Depending on context, Japanese could also use other words, such as:

• メール = email
• 手紙 = letter
• 連絡 = contact / communication

But メッセージ is perfectly natural here.

を marks the direct object of the verb.

The verb here is 送りました, from 送る, which means to send.

So メッセージを送りました means:

• sent a message

More literally:

• message + direct object marker + sent

So を tells you what was sent.

送りました is the polite past form of 送る.

• 送る = to send
• 送ります = send / will send (polite non-past)
• 送りました = sent (polite past)

Japanese uses the past form because the action has already been completed.

So this sentence is describing something that already happened: the message was sent.

It comes from the verb 送る.

Conjugation:

• dictionary form: 送る
• polite form: 送ります
• polite past: 送りました

Step by step:

1. 送る
2. change る to the i-stem: 送り
3. add ます → 送ります
4. past of ます is ました → 送りました

So 送りました = sent in polite speech.

Japanese often leaves out the subject when it is understood from context.

So お礼のメッセージを送りました could mean:

• I sent a thank-you message
• We sent a thank-you message
• in some contexts, even he/she sent a thank-you message

But in many real situations, especially if the speaker is talking about their own action, listeners will naturally understand it as I sent a thank-you message.

This omission is very normal in Japanese and happens all the time.

The お in お礼 is an honorific/polite prefix.

It often makes a word sound more polite, softer, or more natural in everyday speech.

• 礼 by itself means thanks, gratitude, courtesy, or bow
• お礼 is the common everyday form when talking about thanks

In many cases, native speakers would strongly prefer お礼 over bare 礼 in normal conversation.

This お / ご prefix is very common in Japanese, for example:

• お名前 = name
• お金 = money
• ご説明 = explanation

Not every noun can take it freely, but お礼 is standard.

Yes, it is natural and easy to understand.

It sounds like a polite, straightforward statement. Depending on context, native speakers might also say:

• お礼のメールを送りました = I sent a thank-you email
• お礼のLINEを送りました = I sent a thank-you message on LINE
• お礼を伝えるメッセージを送りました = I sent a message to express my thanks

But your sentence is completely fine as it is.

Normally, no.

Although お礼 can sometimes refer to a token of thanks, return favor, or gift in appreciation, in the phrase お礼のメッセージ, the natural reading is a message expressing thanks.

That is because message fits very naturally with thanking someone, not with the idea of a reward.

So in ordinary context, learners should understand this as a thank-you message.

In normal Japanese writing, spaces are usually not used.

The sentence would normally be written as:

お礼のメッセージを送りました。

Spaces are often added in learning materials to make it easier to see the parts of the sentence.

So the spaced version is helpful for study, but the standard real-world version is without spaces.

A rough word-by-word breakdown is:

• お礼 = thanks / gratitude
• の = linking particle
• メッセージ = message
• を = direct object marker
• 送りました = sent

So a very literal gloss would be:

• (I) sent a message of thanks

That is close enough to the English meaning, but the most natural English translation is usually:

• I sent a thank-you message.

This is a good example of how Japanese and English line up fairly well in meaning, even if the grammar works differently.