noun
sender; source (of a transmission)
Used in technical or IT contexts for the origin of a message, email, or data transmission.
メールの送信元を確認してください。
Please check the sender of the email.
このデータの送信元は不明です。
The source of this data is unknown.
差出人 is used for the sender of physical mail or formal correspondence, whereas 送信元 is used for electronic transmissions.
Compound of 送信 (transmission) and 元 (origin, source).