Stopping emails

Hi,   Does anyone know how to stop receiving emails about posts that you are no longer involved in? 

I thought there would be a stop sending/receiving emails button but I couldn't see one.   It's not that I'm no longer interested in the posts, it's just that my inbox gets pretty clogged up what with receiving four emails each time and I thought I would stop some of them and just catch up by looking at the forums page instead. 

Ideas anybody?

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