SortCentre is a proprietary application that combines email, CRM, help desk, and project management features. A typical problem with project management tools like Basecamp and communication tools like Slack is that you cannot force your outside clients and vendors to use your system. Email is still the lowest common denominator.
SortCentre turns each thread of email into a project with a todo list and file sharing. You can merge threads, move individual messages to a different thread, edit the subject line without spawning a new thread, assign projects and departments, set priorities and status, and add internal comments. You can also share accounts with other users in your organization so that you can collaboratively manage external communication.