How to add additional mail converter boxes in Vtiger 7

How do I add additional Mail Converter mailboxes in Vtiger 7?

This took me a frustratingly long time to figure out.

I eventually found the answer on GitHub.

https://github.com/milan9615/vtiger7/blob/master/config_override.php

All you need to do is edit Vtiger7\config_override.php

Hope that helps!