Switch on 'new email message' email...

I have the text in "Email template for notification about new messages in the inbox." set-up but can't find where to allow members to receive an email when they receive a new message on this site email system!

Does a user only recieve a notification email when the user writing the message clicks on "Notify by e-mail"... or can a more definite method be activated?

Any help? Thank you.

Hello internal mail system contain only 2 ways with notification :
1. Send email notification that you can find in email templates
2. Send copy of message to physical email addres of recipient

OK thanks, that is what I thought. So there's no way to make it standard for a user to receive a notification via email about a new site message from another user?