Affordable Email Providers with VERY strong Anti-Spam tools

Former lurker here, finally posting to ask for assistance:

We have about 200 email accounts. Our current email provider basically has a spam filter, that's it. The nature of our industry means that there is a DELUGE of spam, phishing, malware, etc and NONE of it is being blocked by the provider.

I need an affordable email provider that has VERY strong anti-spam tools; on par with or better than Google's, and affordable. Have to also offer a custom domain.

The issue is that I cannot simply use Google. I desperately WANT to use Google, since it would solve almost every single problem we have while being in our budget. But higher ups are very against Google, Apple, Amazon, etc (thinking they're unsafe, when the single biggest threat to us is one of our MANY computer illiterate staff creating a data leak). The provider must not have any news record of a prior successful hack against them. Bosses are also ridiculously cheap, so cost is a huge issue.

You can imagine my headache.

If anyone can suggest a list of good providers for businesses (we don't expect them to be free, just cheap).

EDIT: Thank you very much for the replies. I think I have a few solutions with which I can present to my superiors. Hopefully it works out!