noun
Refers to the person or entity that initiates a communication, such as a phone call, email, or data transmission. Common in technical and everyday contexts.
メールの発信者を確認してください。
Please check the sender of the email.
発信者番号を非通知に設定する。
Set the caller ID to private.
送信者 also means 'sender', but is more common for postal mail or data transmission, while 発信者 emphasizes the act of originating a communication.
Compound of 発信 (transmission, sending) + 者 (person). The reading is standard on'yomi.