• 打开 Terminal
• 输入 defaults read com.apple.mail UserHeaders，回车
• 显示有 The domain/default pair of (com.apple.mail, UserHeaders) does not exist
• 输入 defaults write com.apple.mail UserHeaders '{"Reply-To" = "reply-to@address"; }'
• 禁用此功能 defaults delete com.apple.mail UserHeaders

注意：此设置会忽略 GUI 中的 Reply-To 设置