Sincerement is sincerely in French
Fish is "kala".
to end a perfect letter you could write sincerely, sincerely yours, very sincerely, or very sincerely yours
"Turpa kiinni"
诚挚Chéngzhì
At the end of the letter write yours sincerely.
You could write either, Yours Sincerely (if you know them) or Yours Faithfully (if you don't know them).
"[ole] hiljaa!" ("[be] quiet"), or if provocatively "turpa kiinni" ("shut your mouth")
You'd need a keyboard with umlauts, or you have to use unicode characters.
dear hotel adress: what are your rates sincerely......
The Finnish language is suomi (Finnish) or suomen kieli (Finnish language) in Finnish.
Dear Dummy, 10,000 Years Sincerely, Captain Obvious