Just a roughed out example of the structure we can use for the trigger system...

trigger.cs

using System;
using System.Collections.Generic;

namespace Trigger
{
    public class TriggerEvent
    {
        public int Id;
        public TriggerEventType Type;
        public DateTime EventDateTime; //UTC plz'
        public int OrderId;
        public Guid TransactionId;
        public string EventData; //json object? would be the data 

    }

    public enum TriggerEventType
    {
        EmailClick = 0,
        EmailOpen = 1,
        EmailForward = 2,
        //EmailUnopen = 3,
        //EmailReply = 4,
        EmailBounce = 5,
        SMSReply = 6,
        SMSBounce = 7,
        VoiceHotKey = 8,
        VoiceBounce = 9

    }

    public class Trigger
    {
        public int Id;
        public bool Global; //flag if the trigger is a global trigger 
        //(ie. SMS replies should all pass through our system to be stored and checked for a 'Stop' request)
        public int AccountId;
        public int ContactId;
        public in OrderId;
        public List<TriggerEventType> TriggerEventTypes; //do we want to allow for multiple trigger event types to be associated with a trigger
        public string WebhookUrl; //url we'll be posting to
    }
}