Antivirus for Business - for Free

Not too many offerings, but here is a list

Comodo
Immunet
Nano - reviews are not convincing currently to use it.
Unthreat
  refer to
  https://www.raymond.cc/blog/free-antivirus-for-corporate-commercial-and-educational-use/
Forticlient

  also see comments the raymond.cc site

Avast for Business
  also see the comments.
  is free, see
    https://www.avast.com/avast-for-business
  Sign Up Here
    https://id.avast.com/en-ww/?target=https%3A%2F%2Fbusiness.avast.com%3A443%2F#register
  Login here:
    https://id.avast.com/?target=https%3A%2F%2Fbusiness.avast.com%3A443%2F#login
  See comments about the certificate and how Avast uses https traffic
    http://smallbiztrends.com/2015/02/avast-for-business-security.html