The nice people at AntibodyMX said they'd de-spamify my email for me for free provided I wrote a review. They didn't say it had to be a good review :-) so I took them up on it.
I've previously been rather sceptical about such services. There are obvious concerns about privacy from having all your mail go through someone elses systems instead of going - as far as is possible - straight from the sender to you. If you use TLS (and you should) then even if your mail transits someone elses network, they won't be able to read it. With an outsourced service like AntibodyMX's, they can, because mail is sent to them and they then forward it on to me. That they can see the plain-text of my email is, however, necessary for the filtering to work. And in practice, it's not a significant concern at least for individuals, because my mail just isn't that interesting.
My other source for scepticism was that they probably couldn't do a better job than I could. Indeed, because their service has to work for everyone there are ways in which they can only possibly do a worse job at filtering mail than I can. For example, I can throw away all mail in Chinese, Russian, Japanese and Hebrew, because all mail in those languages is unreadable so even if it's not spam (yeah right) I still don't lose out by ignoring it. They can't do that, because I'm sure they have some customers who get some legitimate mail in weird languages that aren't written right. Without tools like that, then surely they can't do a better job than me - after all, the software they use is the same that's availabe to me, and I've been successfully de-spammifying my email for years.
So why did I switch? Simply because I got fed up maintaining my anti-spam systems. They eat valuable memory and CPU - and eat more by the day as I have to keep adding more filters to combat spammers' evil imaginations. Maintaining all that takes time. Due to having more interesting things to do, I was beginning to fall behind on keeping my filters up to date, and more spam was sneaking through. When I got the offer to use their services for free, I decided to take them up on it. After all, there's no real downside. If it doesn't work as well as advertised, I can trivially switch back to doing the job myself.
But I won't be switching back to doing the job myself. The AntibodyMX service Just Works.
That, however, is with the service being free. It's a different matter entirely if you have to pay for it. According to their website, prices start at £115 a year. When you think about how much time your company's sysadmins put in to spam control, it's a no-brainer and is easily worth paying. It's only really worth thinking about if privacy is particularly important to you. I wouldn't want, for example, my doctor or solicitor or MP to use any such service. Not because they can't trust the service providers, but because they shouldn't trust anybody. Doubly so if using a service provider in another country.
For personal use I think £115 would be a bit steep. It is worth paying for, I'm just not sure how much I'd shell out.