If you look around the options that come with your email, there will be a 'spam' option. If you tick the box next to the offending email and choose 'send to spam' or 'report as spam' or similar (however it is phrased) then your email will recognise it a spam in future and put it straight into the spam folder.
the spate does die away after a month or so. They are sneaky in that the email is filled with an image so there is no text for the spam filter to "read"