The way that I understand mail subscriptions work:
- The user subscribes to a thread with immediate notifications
- The user gets sent the first notification right away
- If the user is not active on the site (logged in, clicking something) we pause notifications by default until they are active again (this is to keep them from coming back to 600 emails overnight, standard forum behavior)
- If the "don't pause" option is selected (it is OFF by default), it overrides this default and the user should get immediate notifications from all relevant subscriptions until this option is either deselected or they change their sub options. This often leads to an overwhelming amount of email in a short period of time on active threads.
So, the questions are:
- Are you set for receiving "immediate" subscriptions for your threads?
- Is the "no pause" option selected?
- Are you getting any email at all?
From what I know, if you have all that set, you should be getting a ton of emails. If you then uncheck the "do not pause" option, you should only get one email per subscription.
Logging in and logging out should not impact the system, but if you notice that it is, please continue to report it.