手紙 and 葉書: exchanging letters and postcards
Distinguish the written medium from sending and receiving actions.
Writing a letter
手紙 (てがみ) means letter. 「友人に手紙を書きました」 means writing a letter to a friend.
「手紙は書きましたが、まだ送っていません」 says the letter is written but not yet sent. Separate writing from dispatch.
Sending a postcard
葉書 (はがき) means postcard. 「旅先から葉書を送りました」 says a postcard was sent from a travel destination.
「葉書の裏に絵を描きました」 means drawing a picture on the back of a postcard. A postcard can be described through a picture rather than writing.
Recipient and origin
「母から手紙が届きました」 says a letter arrived from the mother. から identifies the sender's side.
「友人への葉書」 identifies a postcard for a friend. への gives its intended recipient without establishing receipt.
Does writing a letter establish that it was sent?
Show the answer and why
No. Writing and sending are separate actions.