From PhpCOIN Documentation
phpCOIN maintains a HelpDesk function, wherein a customer will send you an email about an issue and your replies to the "ticket", and any subsequent client messages, are all accessible from a single web-page. This makes it much easier to track the progress of an issue than traditional email in separate messages.
The ticket can be entered by a logged-in client, or by an administrator on behalf of a client.
Some clients will simply hit "reply" in their email client rather than login to your website. phpCOIN has a script to be run on a schedule that can check an email account for new support requests, or replies to an existing request, and either create a new ticket or append a response to an existing ticket accordingly.
The admin parameter to disable HelpDeskwill remove all menu links and buttons that reference helpdesk, and if a surfer tries to access helpdesk data directly via URL parameters they will receive a "disabled" notice.