As artificial intelligence increasingly mediates everyday communication, people may no longer be the sole authors of messages they send. In a five-condition between-subjects experiment, participants responded to an unpaid-loan conflict using self-expression, editable Al-assisted messages, or non-editable agentic-Al messages in polite or assertive styles. We examine perceived control, psychological ownership, responsibility attribution, willingness to send, and catharsis. By comparing Al involvement and message style, the study tests whether retaining editability changes how people experience authorship, responsibility, and the decision to send an assertive message.