I just decided to download this plugin especially for sending to different email addresses from checkboxes selected. The pipe function for an array was not working. It looks like the latest release from yesterday introduced a bug. But according to a post there was a simple fix and now it is sending multiple emails from the checkboxes and the message body is able to get the _raw_ value from the checkboxes.
The quick fix is to edit wp-contact-7/includes/classes.php
Around line 599 in the classes.php file look for this line of code: $submitted = trim( $submitted ); and comment it out like this:
//$submitted = trim( $submitted );
With this fix I was finally able to have the pipe function working properly. Give it a try.