We have the following set up for our SLA.

When a contact first writes in, the response due and resolution due dates are set.

When one of our agents responses, the response due goes away.

When a ticket gets a response from the contact, it appears to reset the timer to 12 hours on the response due date. This doesn't seem to reset if the primary contact for the ticket writes in. Is there anyone else that can trigger the response due date to reset (secondary contact?)

We set up a second SLA for resetting response time, however internal emails we getting triggered because the filter criteria was not picking up the email domain as an exception (that would be a good filter criteria.)