Whoever interacts with a ticket, creating it, or simply replying, should be automatically subscribed to it, as if you forget to subscribe and someone replies to it, if you don't go and check, you won't see it
There is already a setting in the UserCP to subscribe / "watch" tickets created by said user, it needs to be renamed to "Subscribe to my new tickets".
For the subscribe on reply, I could add another setting for this.
That would be very neat!
And I do believe that both of these options should be selected by default as this is the default behaviour that you would expect in an issue tracker.
PS: I love Traq
PS2: Check the SPF record of traq.io: emails are considered as spam
With the faster release plan, I'm going to spread features and enhancements across more 3.x releases.