If one or more of your contacts have more than one email address: a group containing such contact will display all email addresses when the group is entered in your iOS mail client.
Leaves you as the sender to either send to all addresses or to sort out which.
For my purposes this "annoyance" makes the app worthless.
Author says its an iOS fundamental he cannot avoid.
Sorry I bought it.
Fast Eddie 1011 about Interact Contacts, v1.1.3