Private messages have now been configured to include the senders email address as the FROM address.
This means that if you send a Private Message, your email address will be included regardless of whether you have set it to not display in your profile.
The reason for this change is that many people were not reading the note at the bottom that said "DO NOT REPLY TO THIS MESSAGE! " etc, and replies were ending up in an unread system email account rather than going to the intended recipient.
--- If you don't wish to receive these Site News emails in future, please switch it off in your Profile.