Trigger a Follow-Up Task When an Email Task is Inserted

TaskTriggerHandler

// Trigger Handler to create a follow-up task when an email is send through Salesforce's "send an email button"
// based off of Kieren Jameson's Cooking with Code: A Tasty Trigger Treat 
// http://womencodeheroes.com/2015/07/cooking-with-code-a-tasty-trigger-treat-apex-triggers/
 
public class TaskTriggerHandler {
    // declare a method, which accepts a list of tasks (EmailList) as a parameter.
    public static void createNewTask (List<Task> EmailList) {
    
        // Set up Due Date variable for the new tasks, which is 1 month from today
        Date dDate = Date.today(); // set's today's date
        dDate = dDate.addMonths(1); //adds one month
        // TODO: set # of months in a custom setting? 
        
        // Create list to keep the New Tasks you want to create in the database
        List<Task> newTasks = new List<Task>();
            
        // Loop through all the emails (tasks) that were just added by the trigger
        for (Task t : EmailList) {    
            // filter criteria for when the trigger should fire
            // if the subject starts with "Email:" && it is attached to a contact
            // TODO: Could you move the string to filter by into a custom setting? 
            if(t.subject.startsWith ('Email:') && t.WhoId != null) {
                // create --> new task called ToDoItem. 
                Task toDoItem = new Task (
                    // details of the new tasks being created
                    Subject = 'Follow Up on: ' + t.subject,
                    status = 'Not Started',
                    ActivityDate = dDate,
                    whoId = t.whoId,
                    Priority = 'High'  
                );
                newTasks.add(toDoItem); // populate list of new tasks with each task
            }
        }
        Insert newTasks; // insert into the Salesforce DB outside of the "for Loop".      
    }
}

Apex Test Class https://gist.github.com/forcethesales/a92526f043ac65d1dfe09f985d2c5360

Trigger Handler https://gist.github.com/forcethesales/0e2e39a1ed74119eac5dbcdc23f8de99

Task Trigger https://gist.github.com/forcethesales/337b0fbeceefffa89176592effbbdd47