Members List with email checklist

Ok so this is a little tough to explain but wondering if anyone can point me in the right direction. My clients current site is running on Drupal I am converting it to Wordpress bout 90% done with the whole project. On the current site they have a section with a list of all the sites members in a table split in to 3 columns. First column is the members name, 2nd column is the members email address and the 3rd column is a check box that you can click to say I want to email this member. You can check as many users as you want and when you click submit it generates a paragraph of all the users emails separated by a semicolon that you can copy and paste in to your email application to send a mass email. Anyone here know of a good way to do this or point me in the right direction for it? I have a total of like 145 users registered, site is running Wordpress 3.5, Buddypress 1.6.2, using Gravity Forms for user registration and other components (also asked on their boards they said no simple way of achieving this with Gravity Forms)..

Hope someone can help! Thanks!