O2 and Hotmail alerts

Hi,
Don't know if anyone else has experienced this....
My son's phone (Nokia) has started to receive copies of new emails going into my Hotmail account.
Upon investigation the Options set-up on Hotmail, found out that this had been activated without my knowledge. Could this have been done by O2 to increase income? (they had my son's number + my hotmail address when we registered after purchasing the phone).
Anyone else experinced this?