You were emailed a private invitation on behalf of your Trade Association, University Alumni Association or other affiliated networking group. You were included because an administrator inputted your name and email into their community member roster. If you are not interested, you may simply unsubscribe from invites.
FYI- you will receive a new invitation each time you are added by an admin to a new networking community powered by Zenvoy. Check out more details on being invited to a networking community. In addition to your initial invitation, you will also receive a few automated invite reminders over time.