delayed delivery; deferred transmission
Computing term for sending data, messages, or emails at a scheduled later time rather than immediately.
This email software has a delayed delivery feature.
I set up deferred transmission so the email will arrive tomorrow morning.
予約送信 is a more common term for scheduled sending, while 代行送信 is a less frequent synonym often used in technical contexts.
Compound of 代行 (acting on behalf of) and 送信 (transmission), literally 'proxy transmission'.