送信 and 受信: the sending time and the receiving time
Compare a sent-mail record with a received-mail record, keeping sending, receipt, and reading separate.
The action on the sending side
送信, read そうしん, means sending a message or information. 九時にメールを送信しました。 says that an email was sent at nine o’clock.
送信済みですが、相手の受信は未確認です。 says that sending is complete, but the other party’s receipt has not been confirmed. Completion and lack of confirmation concern different actions.
The action on the receiving side
受信, read じゅしん, means receiving a message or information. メールを受信しました。 says that an email was received.
受信したメールを保存しました。 says that a received email was saved. Receipt and saving are stated, but reading the content is not.
Two timestamps and whether the message was read
送信は九時、受信は九時二分でした。 says that sending occurred at nine o’clock and receipt occurred at two minutes past nine. Read the two explicitly stated times separately.
A received email may still be unread. Identify the action reported by each description, such as 受信, 保存, or 読んだ.
Does 九時にメールを送信しました。 establish that the other party received the email at nine o’clock too?
Show the answer and why
No. It says that an email was sent at nine o’clock. The other party’s receipt time requires a separate record or statement.