@M. Evans, Thanks for posting in Q&A. Based on your request, it appears that you are facing security issues within your Microsoft 0365 environment. You have mentioned that you have implemented conditional access, but you are uncertain if the deployment was carried out correctly, and you are looking for additional measures to ensure the hardening of your security infrastructure.
Securing a system of this complexity and scale requires a comprehensive approach to security. I would suggest you review Microsoft's security guidance and best practices for Microsoft 365.
Meanwhile, you can post in Microsoft 365 community to get more suggestion:
Microsoft Online Services are some of the largest enterprise and consumer cloud services globally, and it is Microsoft's top priority to keep customer data secure and maintain customer trust. Securing a system of this complexity and scale is effective only when security is integrated during the initial design process. It requires a robust threat detection system with prompt responses from both automated systems and highly skilled engineers. Continuous assessment and validation of these systems is essential to ensure secure configurations remain intact and previously unknown vulnerabilities are identified.
For Microsoft 365 security training, after researching, I find one for your reference:
https://video2.skills-academy.com/en-us/training/modules/security-in-m365/
Hope the above information can help.
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