AO - I had the same problem about a month, 6 weeks ago. I was getting 20/30 a day.
I have never had spam problems before, perhaps one or two emails a week, if that, despite my email address being all over the internet due to me running a website.
Anyway, after a month or so, it all stopped. Just like that, as TC used to say. No idea why it started or indeed stopped as it did.