BuddyPress.org

@ risi hi, this plugin has not been updated since 2009, and we dont know whats going on with Giovanni who owns the plugin as all effort to contact hin proved abortive. i have used the plugin before but i got error relating to Zend so i removed it which is what i will Advice u to do for now. i think some guru will look into it may be they can write something similar. but you can also use Invite anyone plugin, which is what am currently using but u have to input email manually. here is the link

https://wordpress.org/extend/plugins/invite-anyone/

regards