update email error message on registration form

inc/class-validate.php

@@ -150,7 +150,7 @@ public function signupUserBC() {
 				$valid  = $this->isWhiteListedDomain( $domain );
 
 				if ( false == $valid ) {
-					$bp->signup->errors['signup_email'] = 'Please use an email address from an authorized domain.';
+					$bp->signup->errors['signup_email'] = 'Your email must match the Internet domain name of your organization.';
 				}
 			}
 		}