I personally love the supscription e-mails, because they are helping me to keep track what is hapening on our forums.
But sometimes it gets a bit annoying when you are activ in like 5 or more forum discussions and you are still getting these e-mails. But in fact they are useless, because you are visiting the forum and getting the in-forum notifications anyway.
So our idea was, to disable those e-mail supscription messages for a user for the time he is online in the forum.
Hope you guys got my point^^
User is offline---> Subscription emails
User is online---> No subscriptions e-mails during that time