In my first language (Thai), a typical formal letter usually has quite a similar format to English letters, with one exception...
Between the last paragraph of the body of the letter and that "Yours sincerely" line, we usually insert another short paragraph, usually with only one sentence, typically can be translated literally to,
which means something similar to the phrase "just so you know".
Today I was asked how one should translate that line to English. I realized at once that I never wrote that line in English before, because I haven't seen such phrase used in any formal letters. And to me, saying "just so you know" sounds almost rude.
If I really have to translate that line, how should I express it in a more polite way?
(I am thinking about "Pleased to have you informed," but not sure if it really works.)