Exactly. What mkg wrote.
Your son account was created using your credit card, he is your son - you can demand ability to monitor his emails .
In my opinion it's stupid, you do not ask for transcript of all his phone calls or personal conversations - how's email different?. But it's your right as a parent if you choose to.
None of email providers will offer this to you. You have to google for monitoring software or keystroke recorders.
- Независимость - это когда в 20-й раз наступаешь на одни и те же грабли, а русские уже ни при чем....