Concat all values from a sharepoint column into an InfoPath List box or text field

Hi all, I am trying to concat all the e-mail addressess in a SharePoint Column 'titled e-mail' to a list box, or text field in info path. I need these mail addressess so I can test a rule against them, so if the curent user's email is not contained in the concated email list box then the form will swap views.

So my sharepoint list is

Name   email Address:

Bob       bob@mycompany.com
John      john@mycompany.com
Harry     harry@mycompany.com


In info path I require a list box or text field 'called approvers' to concat those email addeesses as such:

bob@mycompany.com;john@mycompany.com;harry@mycompany.com

I then have a curent user text box, that links into the get user profile by name web service
and populates the curent user's email address.
I can then create a rule that if the approval box does not contain current user, switch views.

Now I've tried using a list box and with a data connection hooked it up to the email list column. Great, all the email addresses appear in the list box. However, the first value is blank as default value is set to none) so the rule cannot compare against the other email addresses in the list box?

Any idea how I can achieve this?