Email for PM change

[wolfey]

OK
I would like to change the body of the email sent to users when a PM is received, currently the email will read:
Dear $touserinfo[username],

You have received a new private message at $vboptions[bbtitle] from $fromusername, entitled "$plaintext_title".

To read the original version, respond to, or delete this message, you must log in here:
$vboptions[bburl]/private.php

This is the message that was sent:
***************
$plaintext_message
***************

I would like to use a custom field I have setup to display the users "Real Name" I Have that inputed into "field2" of their profile
I dont know where/when the $fromusername collects the name...so I cant just put $bbuserinfo[field2] ? Can I

How do I do this?