Recommendations for email spam protection?

My hosting company's spam protection has been great for years but even that is now starting to get overwhelmed with the increased levels recently. For my own email account(s) on my domain, it used to trap around 4 or 5 a day and 3 or 4 a week would get through. Its now trapping 20-30 a day but 10 a day are getting through. One of my customers has had to close an account as 300 a day were getting trapped and 100 were getting through.

I'm prepared to look at paying for a service that I can try. And then recommend this service to my hosted clients that are badly affected. So, who's using what and do they recommend it? I'm quite happy to see affiliate links if gives you or me a kickback.

Thanks, Graham