Your traditional spam service filters email based on sending-server compliance & reputation and received email content while trying not to block emails that seem legit.
But, spammers and hackers are getting smarter by sending emails from innocent compromised email accounts and those emails are designed to dodge spam content filters and include links to websites that are also hacked and loaded with ransomware code or viruses that can infiltrate your office network.
The biggest threat for a company is assuming that all team members will have the intuition to recognize these emails that slipped through and delete them. Spam by itself is a nuisance, but the real danger is ransomware, phishing, and viruses. All it takes is an infected PC on your network and the infection would spread within minutes on all infected Pcs. SpamVault solves this problem with a 99.98% accuracy.