Our (free) forum providers have turned on a system which sends you an email highlighting new threads et cetera. Whilst members may find these useful in some capacity, there is an unsubscribe option within the body of the mail.
Please accept our apologies for the lack of advance warning regarding this.
Just to summarise what we know so far from a couple of members:
the unsubscribe link takes you to a page where you can choose which events you wish to receive emails for and which you do not. The options in most cases are "immediate", "smart" or "never". The first and last of these are self-explanatory but I have not found the meaning of "smart" in this context.
and from a Proboards member of staff via TheBlackFerret
Smart means that you'll only be notified once per item until you've viewed the item that notification is related to.
Using bookmarked threads as an example: If your bookmarked thread gets a response you'll receive an email notification for it. But if you haven't visited the thread yet since the response you were emailed about and it receives another response you won't receive an email notification for that response and any following it. This process will continue until you've visited the thread, after which you'll receive an email notification for the next response just like the first step.
This is different from Instant which would give you an email notification for every response to a bookmarked thread regardless of whether or not you've read the thread.