letter received; correspondence
Formal noun used mainly in business or official contexts to refer to a letter or correspondence that has been received. Often seen in phrases like 来札を拝見する.
Thank you for your letter received the other day.
I have confirmed the contents of the correspondence received.
Compound of 来 (rai, 'come') and 札 (satsu, 'tag, card, letter'). The combination denotes a letter that has arrived. The exact historical derivation is uncertain, but the kanji are conventionally associated with the meaning.