Blocking Personal Gmail Access While Allowing Official Emails Through PFsense Firewal

I need to block access to personal Gmail accounts while allowing employees to log in to their official Gmail accounts (any domain except @gmail.com).

Current Setup:

  • Network managed through PFsense firewall
  • Considering the installation of the SquidGuard package

Specific Requirements:

Questions:

  1. What is the best method to achieve this using PFsense?
  2. Is installing the SquidGuard package a viable solution? If so, how can it be configured to meet the above requirements?
  3. Are there any alternative or more effective solutions to accomplish this task securely and efficiently?

Any advice, configuration tips, or alternative recommendations would be highly appreciated.

Thank you in advance for your assistance!

This is not something that pfsense or really any firewall is really able to do well. We use https://www.saaslio.com/ for this.