Lähettäkää tosite vahinkoilmoituksen mukana.

It is the second-person plural imperative of lähettää, meaning to send.

So lähettäkää means send! or, more naturally in English, please send.

This form is used:

• when speaking to more than one person, or
• as a polite way to address one person in instructions, customer service, and official language.

Yes, grammatically it is an imperative form, so it is a command or instruction.

However, in Finnish this does not automatically sound rude. In forms, websites, official letters, and customer-service instructions, this is a very normal way to say what the customer should do.

English often adds please, but Finnish often leaves it out when the context is already polite or formal.

So Lähettäkää tosite... is best understood as something like:

• Please send the receipt...
• Kindly send the document...

rather than a harsh order.

Because in an affirmative imperative sentence, a total object is usually in the nominative.

Here, the sentence tells you to send the whole document, so tosite is a total object.

Compare:

• Lähettäkää tosite. = Send the document / receipt.
• Te lähetätte tositteen. = You send / will send the document / receipt.

In many non-imperative sentences, a total singular object is often in the genitive form, but in the imperative it is typically nominative.

So this is a very common Finnish pattern.

Tosite is a somewhat formal word meaning a supporting document, proof, voucher, or often a receipt.

The exact English translation depends on context. In insurance, reimbursement, or official paperwork, it often means:

• a receipt
• a proof of payment
• some other document that proves the claim

So it is broader than just one exact English word.

Because mukana normally takes a word in the genitive.

The pattern is:

X:n mukana = with X, together with X, included with X

So:

• vahinkoilmoitus = damage report / claim form
• vahinkoilmoituksen mukana = with the damage report / together with the claim form

That is why you see vahinkoilmoituksen, not vahinkoilmoitus.

Here mukana means with, along with, or included with.

It does not mean physical companionship in the same way English with sometimes does. In this sentence, it means that the supporting document should be sent together with the damage report.

So the idea is:

Send the receipt as an attachment / enclosure with the damage report.

Because mukana is the more natural word when one thing is included with another thing.

• vahinkoilmoituksen mukana = with the damage report, enclosed with it
• vahinkoilmoituksen kanssa would sound less natural here

Kanssa often means with in the sense of together with or in company with, especially with people, and it is not the usual choice for talking about sending one document enclosed with another.

So in this sentence, mukana is the idiomatic choice.

It is a compound word:

• vahinko = damage, loss, accident
• ilmoitus = notice, report, notification

So vahinkoilmoitus means something like:

• damage report
• claim form
• accident report

The best translation depends on the situation, especially in insurance or claims contexts.

This is a very typical Finnish compound: two nouns joined into one longer word.

Because Finnish has no articles.

So tosite can mean:

• a receipt
• the receipt
• a supporting document
• the supporting document

The context tells you which one is intended.

That is why Finnish learners often feel that the sentence looks a bit more general than the English translation.

Yes. Finnish word order is fairly flexible.

This sentence has a very natural instruction-style order:

• Lähettäkää = verb first
• tosite = object
• vahinkoilmoituksen mukana = adverbial phrase

A different order, such as Lähettäkää vahinkoilmoituksen mukana tosite, would still be understandable, but it may shift the emphasis slightly.

The given order is a normal, clear way to present an instruction.

Roughly as lä-het-tä-kää, with the stress on the first syllable, as usual in Finnish.

A few important points:

• ä is a front vowel; English does not have a perfect match
• tt is a long consonant, so you hold it slightly longer
• ää is a long vowel, so that final syllable is longer too

Finnish spelling is very regular, so once you know the sounds, the word is pronounced very close to how it is written.