Secure S/MIME Email Setup in Outlook

I'm looking for a professional who can help me set up sending encrypted emails using S/MIME encryption from my M365 account via Outlook Desktop.

Key Requirements:
- Configure S/MIME encryption for email security
- Ensure compatibility with multiple email providers, like Gmail and Yahoo
- Set up automatic generation and management of encryption keys

Ideal Skills and Experience:
- Proficient in Microsoft 365 and Outlook Desktop
- Previous experience with S/MIME encryption set up
- Knowledge of cross-platform email encryption compatibility
- Familiarity with automated system configuration and management

I have a C# Outlook Addin. I have the E5 M365 license so I am able to use encryption. I can use the manual Encrypt option in the Outlook Ribbon and it works,. MSFT brands auto-decrypt emails. Non-MSFT brands must click a button to decrypt.

I obtained a free s-mime certificate but I don't know how it gets entered into Outlook Desktop app.


This site gives FREE certificates for email encryption:

https://www.actalis.com/activate-s-mime-certificate

I found the above site by reading this article:

https://thomas.vanhoutte.be/miniblog/where-to-get-a-free-s-smime-e-mail-certificate-3-options/

https://www.actalis.com/s-mime-certificates